glorysteelwork-blog - Tumblr blog

glorysteelwork-blog · 6 years ago

Text

Welding Process Details about QU Crane Rail

With the development of China’s port industry, the crane’s lifting tonnage and operating efficiency are constantly expanding, and the adaptability to the

QU crane rail

is also put forward higher requirements. In the past, the way of connecting the QU crane rails through the fishplates has limited the running speed of the crane. Especially with the increase of the running speed of the crane, the impact of the fishplate joint on the crane roller is large, which affects the service life of the roller. The connection of the QU crane rail to the fishplate connection to welding is precisely to meet this requirement, in order to achieve the purpose of improving the comprehensive economic benefits of port loading and unloading. Compared with the fishplate connection, the welding method has strong integrity, high reliability, without post-maintenance cost, and can be adapted to the crane’s operating mechanism to the maximum extent, but there are also problems such as high cost, complicated process and long construction period.The material of the QU120 rail is made of U71Mn. The welding of this QU crane rail made in this material is difficult, mainly because of the following points. The higher carbon content makes the high carbon steel weldment cool after welding, especially in the low temperature season, the quenching performance is sensitive, the martensite structure is generated in the heat affected zone, and the brittle hardening zone is formed, which is easy to crack. At the same time, because the microstructure has effect of stress on the weld metal, this may also affect the crack in the overheated zone. The thermal conductivity of high carbon steel is inferior to that of low carbon steel, resulting in a significant temperature difference between the welded and unheated parts, causing a large stress concentration during welding process, and a tendency to crack when the molten pool cools. When high carbon steel is welded, due to the influence of high temperature, the grain growth speed is fast, part of the carbide is distributed at the grain boundary, the weld seam is weak, and the strength of the welded joint is lowered. During the welding process, the base material is partially melted into the weld metal, which increases the carbon content of the weld metal and is prone to thermal cracking. The liquid metal in the molten pool is exposed to oxygen in the surrounding air for a long time and is easily oxidized. Therefore, strict process measures must be taken to select the appropriate welding parameters to ensure the welding quality.

0 notes

glorysteelwork-blog · 6 years ago

Text

Measures to Maintain Accuracy of Crane Rail Installation

The cleanliness installation of the bridge crane rail is an important factor to ensure its safe operation. However, its solid reliability is an important condition that cannot be ignored. When the overhead crane brakes, a longitudinal thrust is generated. If the car brakes, a lateral thrust is generated. If the large and small cars are braking at the same time, a combined braking force is generated to subject the track to an oblique thrust. If the

crane rail square steel

is installed with one side generally higher than the other side, the overhead crane will move to the lower side as a whole, which will increase the lateral force that the crane rail square steel is subjected to. Thereby, the rail pressing plate is loosened and detached under the action of the above-mentioned forces, and the crane rail square steel is displaced accordingly, causing the bridge crane to run the ramp, the cart is twisted, shaken, unable to stabilize the hook, and is prone to collision and accident. In particular, open-air bridge cranes, in order to prevent wind blowing and tipping, in the non-working state, the rail clamp is on the clamping rail, so the solid reliability of the track laying is particularly important. In addition to the rigid reliability of the crane rail square steel installation, it must be considered for easy replacement. Especially in continuous production sites, this cannot be ignored. For this reason, most of the permanent connection methods such as welding are not used. At present, the crane rail square steel connection generally include plate fixing method and hook bolt fixing method, etc. When the bridge crane is caused by some mechanical or electrical reasons (such as the accuracy of the installation of the wheel, the error of the diagonal, the adjustment of the brake and the asynchronous motor, etc.), rail gnawing will be caused, which is bound to cause large wheel edge to generate a lateral thrust to the crane square steel. This force is transmitted from the rail to the pressure plate (the distance between the pressure plate needs to be adjusted, so the bolt hole is made into a long hole). Even if the pressure plate is installed, the wooden wedge or square pad spot welding is added, and the large-tonnage bridge crane track is difficult to ensure that displacement will not happen, because the platen fixing method has only vertical pressure and no lateral force, the lateral displacement of the track is unavoidable.After years of use on the crane rail square steel, the repair experience proves that the above two joint methods are combined, that is, two pairs of platen joint methods, and a pair of hook bolt fixing methods are effective. This not only exerts the advantage of large vertical pressure of the pressure plate connection, but also ensures that the bottom plate of the rail is not easy to be stringed out, the elevation is constant, and the advantage of the lateral force of the hook bolt fixing method is fully utilized to ensure that the track does not produce side bends. This type of structure ensures that the installation accuracy of the track is not easily changed, and the reliability of the track connection is ensured. It is also not necessary to adjust the track elevation frequently, and the side plate bends the clamping plate nut, thereby improving the utilization of the bridge crane and ensuring its safe and reliable operation.

0 notes

glorysteelwork-blog · 6 years ago

Text

New technology for Fixed Welding about Crane Rail

The traditional rail fixing technology is a hard fixed rail installation process in which the crane rail flat bar is directly laid on the bottom of the track groove, and the pressure plate is directly fixed on the embedded bolt. This connection method has disadvantages such as unevenness of the track groove bottom. The new technology of

crane rail flat bar

fixed welding has solved the shortcomings of the traditional rail fixing technology in use. The new technology of crane rail flat bar fixed welding requires that the crane rail flat bar be welded end to end to form an integral track, eliminating the vibration generated by the rail interface. The steel rail is fixed by the steel rail elastic platen. The 9100 series of pressure plate used with the QU100 rail consists of a pressure plate base, a pressure plate clamp, a high-strength bolt, a nut and a flat washer. The long groove formed on the upper side of the pressure plate clamp can adjust the pressure plate clamp laterally to ensure the straightening of the steel rail and the fitting contact between the pressure plate clamp and the steel rail, and the fixed steel rail of the lateral steel to steel. The high-strength rubber nose in the front section of the platen clamp presses the rail with its elastic force in the vertical direction, and the wheel is loosely broken by the generated bow wave. The rubber nose can also absorb the stress in the axial direction of the rail, so that the pier rail can be in the form of a long rail. A continuous steel backing plate is placed between the rail and the bottom of the track groove, and is fixed by anchor bolts and high-strength cement underneath. The method enhances the lateral stiffness of the rail fixing system and the bearing capacity of the rail. Due to the complete contact between the cement and the steel backing plate, the steel backing plate uniformly transmits the wheel pressure to the cement and the track bottom foundation, thereby eliminating the damage of the concrete at the bottom of the track groove.The track structure of the new technology of rail fixed welding consists of foundation, cement, pressure plate assembly, QU100 rail, embedded bolts, steel backing plate, adjusting bolts and so on. The QU100 rail installation process includes inspection of pre-embedded bolts, installation of steel backing plates, welding of press plate bases, installation of rails, installation of platen clamps, welding of rail joints, tightening of plate clamps and adjustment of rails, and filling of cement. If it is a new project, the embedded bolts can be used directly. The steel backing plate is made of 20mm thick Q235 steel plate according to the drawings. The flatness is ≤1‰, and the position of the bolt hole embedded in the steel backing plate is determined by field measurement. The surface of the steel plate that is in contact with the rail is rust-proof and brushed with anti-rust paint. Before installing the steel backing plate, the loose concrete in the track groove should be cut and the floating ash should be removed and the water accumulated. Install the backing plate as required by the drawing. Use the adjustment adjustment bolts and the pre-embedded bolts to level the steel backing plate. The flatness of the steel backing plate is directly related to the quality of the installation. To reduce measurement errors, try to reduce the height of the instrument.Compared with the traditional rail fixing technology, the new technology of rail fixed welding has been reformed from the installation process and the materials used, which can improve the construction efficiency, shorten the construction period, reduce the loss of the crane body, improve the equipment utilization rate, and greatly reduce the dock track and The basic maintenance work effectively guarantees the long-term use of the rails and has obvious comprehensive economic benefits. It is a new rail installation technology worthy of promotion.

0 notes

glorysteelwork-blog · 6 years ago

Text

International Flat Steel Market Is Expected to Rebound in September

In August, the global steel market continued to differentiate, and the overall performance was down. The European market, which was affected by both weak demand and pressure from export resources, continued to bottom out in August. In the North American market, after the US steel mills announced the closure of several blast furnaces, they raised the price and pushed up the market. In August, the

flat steel

prices in the US market began to rise, and the long profile prices and import prices continued to decline. In the Asian market, prices fell in August, and China’s domestic steel market fell by 4.7% month-on-month. Looking ahead to September, we expect the global steel market to rebound moderately. The weak economy has led to a recovery in demand for steel in Europe. In addition, strict US steel import controls have also led to the selection of global steel export resources in the European market, so the European steel market is under greater pressure. In order to protect the European steel industry, the EU plans to reduce the annual increase in steel import quotas. EU steel companies say the local steel industry is being threatened by imported products. Therefore, the European Commission proposed to take further measures to prevent US steel and aluminum tariffs from causing a large number of foreign steel products to flood into the European market. In late August, the EU plans to reduce the annual increase in steel import quotas from the original 5% to 3% from October 1. The EU’s current steel import quota is based on the annual average import level for the three years from 2015 to 2017. Since then, the import quota will increase by 5% every July 1st. The European Iron and Steel Association (Eurofer) said that imports of finished steel products in the EU increased by 12% in 2018, but the local market grew by only 3.3%. Some analysts said that this may affect Turkey because Turkey has a large share of EU steel imports. The European flat steel market is expected to stabilize in August.The weak demand for long products in Europe is the main reason for the sluggish performance of the long products market. Affected by this, the price of long products in Turkey has been falling due to continued weak demand. Europe is a major exporter of long products in Turkey, as demand is very weak, buyers hope that prices can be lower. It is expected that the long-term European long steel products market will continue to be weak. Under the protection of the US steel and aluminum taxation policy, US steel mills regained market price movements after the price experience fell. However, the rise in US steel prices is mainly due to the behavior of steel mills. The support for continued rise in the latter period is insufficient. It is expected that the US flat steel market is expected to stabilize in August. While US steel trade protection measures continued to push steel prices up in the first half of the year, they also encouraged US steel mills to expand production capacity. According to recent US crude steel production statistics, US steel capacity utilization rate climbed to 80.5%, and output increased by 3.2% over the same period last year. US steel mills began shutting down the blast furnace to cope with market changes. Due to the poor demand in the US construction industry, the price increase of steel mills is mainly in the flat steel market, and the US long products market continues to fall this month. Considering the rising market price of flat steel in the United States, it is expected that the US long profile market will bottom out in September. Korean steelmakers, including Posco and Hyundai Steel, have been seeking to increase the price of their thick steel plates (key materials for shipbuilding and automotive panels) in the second half of the year to compensate for the losses in the first half of the year due to high raw material costs. The drop in raw material prices has made these steel manufacturers very difficult.In September, China entered the traditional sales season. After a few months of correction, China’s domestic steel market is expected to rebound due to the rebound in demand.In September, we believe that the overall market is expected to stabilize and rebound. As the global market decline continues for some time, the global market is actively intervening and adjusting, such as the US steel mills to reduce production capacity, the EU to strengthen import resource restrictions, etc., which will create conditions for the global steel market to stabilize. In North America, the US steel mill’s measures to limit the price increase, although failing to prevent the import market price from falling, the US market price has rebounded significantly, so the US steel market is expected to remain firm in September. The European market has experienced a period of sustained decline. Under the intervention of import resource restrictions in Europe, the European market is expected to stabilize in September, considering the recovery of the international steel market. In the Asian market, China’s domestic steel market entered a peak demand season, and it is expected to rebound in September after a sustained decline in the previous period. In summary, we believe that the international steel market is expected to stabilize in September.

0 notes

glorysteelwork-blog · 6 years ago

Text

Length Extension Welding Process of Crane Rail Square Bar

With the development of the crane industry technology, the whole crane rail square bar design of cranes at home and abroad has adopted more and more steel rail design schemes. The continuity of the whole rail provides more direct and fundamental optimization conditions for the smoothness of crane load operation, which overcomes the influence of the

crane rail square bar

butt joint error (crane rail square bar height difference, crane rail square bar side straightness) when the rail adopts straight edge or the 45° mitre cutting to invoid the vibration generated by the crane trolley load running to the rail interface and the large compressive stress phenomenon caused by bottom support of the rail interface. support. This optimization provides a new topic for the process level. Because the length of the standard rail is limited, to achieve the design requirements of the entire rail, the long welding of the rail is imperative. The crane rail square bar material is generally a kind of high-carbon and high-manganese rolled steel, which has large tendency to weld cracks, and its weldability is poor. If the welding process is improperly handled, the welding quality is difficult to ensure. In order to solve this new problem, the professional technicians gradually improved the welding method of the rail during the trial, practice and summary process.Place the track indoors and use a 1 meter steel ruler to detect the sides of the track to make it straight. When both rails are long, they can be welded on the flat ground. Asbestos pads are used for insulation and post-weld insulation during orbital welding. When the track section is large, it should be 10mm high under the asbestos cloth at the track interface to correct the post-weld deformation. In order to ensure the welding quality of the rail and prevent the occurrence of weld cracks, it is important to select a suitable electrode. According to the characteristics of carbon and manganese in the rail material, it is most suitable to use low-hydrogen welding rod. The electrode has good plasticity and high toughness in the weld metal during welding. This meets the requirements at the rail interface. From the perspective of economy and use, the welding of the rails is realized in three layers using three low-hydrogen welding rods. During welding process, the rail must be preheated and slowly cooled. The rail is preheated by welding with oxygen-acetylene. The purpose of preheating is to prevent martensite hardened structure in the weld heat affected zone and cause crack at the rail interface. Preheating should ensure that the temperature is consistent throughout the preheat range. When the preheating temperature reaches 300 °C to 350 °C, the bottom should be welded and welded flat, and there should be no convex parts on both sides. Otherwise, when the middle layer is welded, the copper plates on both sides cannot be installed. After the rail is welded, the part has a certain welding deformation, which can be straightened by heating with an oxygen-acetylene flame. The outer surface of the rail joint is to be surfaced by a coloring method, and is qualified if there is no crack. If the quality defect is found after the inspection, the welding convex can be scraped off and repaired again.In summary, the welding of the rail usually depends on the chemical composition, mechanical properties, crack resistance of the parent metal of the rail to select the type of welding rod, the size, shape, working conditions and welding equipment and parameters of the welding and take according to the welding object. Corresponding process measures, such as tire assist, pre-weld preheating, post-weld slow cooling, etc., especially temperature control, each step needs to be taken seriously to ensure the quality of the rail welding.

0 notes

glorysteelwork-blog · 6 years ago

Text

Global Dockyards Have Fewer and Fewer Orders

As of early August 2019, global handheld orders accounted for approximately 10% of the existing fleet (GT), a ratio that has created the lowest level in the past 20 years. Glory Steel could offer

CCSA shipbuilding plate

for dockyards. At the same time, global hand-held orders have fallen by nearly 60% in 10 years, and global hand-held orders have fallen to their lowest level in the past 15 years. According to a recent report issued by Clarkson, in the world’s top 10 shipowners (ranked by the total tonnage of the fleet in early August), Korean shipowners’ orders accounted for the highest proportion of existing fleets, which reached 24%. Especially in the container ship sector, Korean shipowners’ container ships accounted for 62% of the existing fleet, which thanks to the 20 super-large container ships that Hyundai Merchant Marine had ordered in 2018. However, South Korean shipowners hold only 9% of the world’s total hand-held orders, ranking fourth in the world. At the same time, Japanese shipowners hold 17% of the existing fleet, second only to South Korea. However, Japanese shipowners hold the largest share of total global hand-held orders, about 21%. US shipowners hold orders in the current fleet ratio of about 14%, ranking third. In addition, although the number of orders held by Chinese shipowners in the world’s total handheld orders is second only to Japan, up to 15%, the proportion of orders held by Chinese shipowners in the existing fleet is only 11%. The orders reduction of the dockyards caused pressure for CCSA shipbuilding plate manufacturers.Among the top 10 shipowners, German shipowners hold the lowest proportion of existing fleets, only 3.6%. In 2008, this ratio was once nearly 60%. Among them, German-owned container ships accounted for less than 1% of the existing fleet, while the figure for 2005 was nearly 70%. Although the Greek shipowner has the largest fleet in the world and has the world’s third largest handheld order volume, Greek shipowners hold only 6.9% of the existing fleet. In recent years, Greek shipowners have been active in the new shipbuilding market for LNG ships. At present, Greek shipowners’ LNG ships hold about 68% of the existing fleet, but their bulk carrier orders account for the current fleet ratio from 2008. 56% to only 3%.By region, in early August 2019, European shipowners’ orders for existing fleets were about 8%, lower than the global average. While Asia-Pacific shipowners accounted for more than 13% of existing fleets. At the same time, European shipowners hold 33% of the world’s total hand-held orders, and Asia-Pacific shipowners account for 53%. These data show that although the current fleet size of European shipowners (604 million GT) is still larger than the fleet size of the shipowners in the Asia-Pacific region (568 million GT), the gap between the two may be further narrowed in the future. According to Clarkson statistics, as of August 16, 2019, the global shipyard held orders for 3,202 vessels 79,524,034 CGT. According to CGT, this figure is about 60% lower than in 2009, the lowest since 2004. According to the latest statistics of Clarkson, the current global fleet size exceeds 1.35 billion GT, of which 57% of the ship’s tonnage is controlled by the six major shipowners. The top 10 shipowners are Greece, China, Japan, Germany, USA, Norway, South Korea, Singapore, Italy and Denmark.

0 notes

glorysteelwork-blog · 6 years ago

Text

Narrow Gap Arc Welding of 45 Degree Mitre Cutting Crane Rails

Usually, the end faces of the welded lifting rails are perpendicular to the longitudinal direction of the rail, but in a few cases, non-perpendicular conditions may occur. Some customers require

45 degree mitre cutting crane rails

. The intention of using the 45 degree mitre cutting crane rails is to reduce the impact on the rails when the crane is walking. Practices have shown that this can reduce the damage to a certain extent, but the impact problem cannot be completely solved. The 45 degree mitre cutting crane rails also exist in certain problems, and the rail joint is prone to lateral misalignment when it’s subjected to the expansion rail pressure. Therefore, the solution to the problem is to weld the 45 degree mitre crane rails into seamless crane rails. Since the end face of the crane rail is inclined, the conventional flash butt welding, air pressure welding and aluminum heat can not be completed. Because if you want to weld, you must cut the bevel into a vertical end face before you can consider welding. Even if the rail is cut into a vertical end face, the flash butt welder is bulky for a lifting rail of a special cross-sectional shape, high-power power source is required, and it is not suitable for field welding. Gas pressure welding requires a prototype heater and corresponding fixture for such a special rail type. Aluminum heat welding also requires the design of special molds, high processing costs and long cycle times. In contrast, the narrow gap arc welding method is more flexible, because only arc welding is to use local heating to weld the rail, and the vertical requirement of the section is relatively low. Although the oblique section welding will have certain difficulty, it may be realized.Narrow gap arc welding method Welding rails are currently widely used in Japan and Europe, and are mainly used for wire welding of railway rails. Among them, Japan mainly use this kind of welding method in the rail welding of the Shinkansen high-speed train, and the aluminum heat welding is abandoned. The advantage of welding the 45 degree mitre cutting crane rail by narrow gap arc welding method is that the quality of the welded joint can be effectively guaranteed, but the mold design and welding process selection are more complicated. The rail bottom of the lifting rail is 200mm wide, and the length of the rail bottom of the inclined end surface is more than 300mm, which is much longer than the length of the general rail weld. The biggest problem with too long weld seam is that they are very susceptible to slag inclusions, incomplete penetration or poor post-forming. Since the bottom of the rail is located at the lowest point of the welding, once the welding defect is not easy to find, it is not easy to produce re-welding. In addition, the bottom end of the narrow end of the inclined end of the mold is more complicated. We should not only consider the slag removal of the long weld, but also consider if the shape is reasonable, and it can not touch the bolts at the bottom of the fixed rail, the design must ensure that the bottom mold can be placed before welding at the bottom of the rail, and normally removed after welding. The design of the rail waist and rail head welding die should fully depend on the asymmetrical shape of the lifting rail at both ends of the oblique section. The mold and the rail body should retain proper clearance, the gap on the acute side should be appropriately reduced, and the obtuse side should be appropriately enlarged.

0 notes

glorysteelwork-blog · 6 years ago

Text

Weak Demand Caused Pressure on European Steel Market

Currently, the European steel market is facing pressure from weak demand, market protectionism and continued high prices for iron ore and coking coal. According to the report of the European Iron and Steel Association, the apparent consumption of steel in the EU 28 countries fell by 2.5% year-on-year to 42.6 million tons due to weak manufacturing. Inventory construction in the distribution chain was lower than the same period last year, which exacerbated the negative trend of end-user steel consumption. In view of the downward trend from the first quarter of this year, the European Iron and Steel Association expects that the apparent consumption of EU steel will fall by 0.6% year-on-year in 2019. Glory Steel could offer

A36 steel plate

.In response to the dilemma, the European steel industry is cutting production capacity. Among them, ArcelorMittal has adjusted its production plan and reduced its production in Europe. It is expected to reduce its production by about 4.2 million tons this year, which involves the company’s steel mill production, like A36 steel plate in Poland, Spain, Italy, Germany and France. In addition, the US steel company recently announced that it will cut production at some steel mills in Europe, and it is expected that more steel mills will take measures to reduce production. However, industry analysts believe that production cuts are not enough to boost the weak European steel market. A36 steel plate is one of the common steel products widely used in manufacturing industry.The risk of higher tariffs imposed by the United States or the United Kingdom on cars produced in the European Union and the negative impact of the WLTP (Global Light Vehicle Testing Program) since the third quarter of 2018 has increased the uncertainty of the future development of the EU automotive industry which is the second largest steel consumption sector in the region. In addition, the European automotive industry is facing difficulties related to the Brexit uncertainty and overall economic slowdown in the UK. The contraction of the industry in 2019 seems to be a foregone conclusion and the car production line may be relocated to Japan. According to the European Automobile Manufacturers Association (ACEA), in the first half of 2019, the number of passenger car registrations in the EU was about 8.2 million, a decrease of 3.1% over the same period last year, and almost all major automobile market countries experienced a year-on-year decline in the first half of the year, including France, Italy, Spain, the United Kingdom and so on. There is currently no agreement on trade negotiations between the United States and Europe, especially in the area of automobile trade. EU car production is expected to decline by 1.4% in 2019.In addition, there is no indication that the European Commission’s import safeguards are contributing to the European market. The European Iron and Steel Association believes that the current design and operation of safeguards is flawed and does not reflect the reality of the EU steel market. The European Iron and Steel Association believes that the European Commission’s decision to increase import protection quotas by 5% is risky, but the European Commission plans gradually increase the overall security quota from 5% to 3% based on recent import data. In addition, the rise in the price of carbon permits has also plagued steelmakers.In the context of global steel overcapacity and increasing imports, European steel market prices have been on the downtrend for several months. The European Iron and Steel Association warned that due to increased delivery from overseas suppliers, steel consumption by European steel producers has declined, which will weaken its profitability. In the first quarter of this year, shipments from EU steel mills to the EU market fell by 4% compared with the same period of last year. Imports from third countries fell by only 1% year-on-year to 10 million tons, accounting for 23.6% of EU steel demand, nearly four points. One of the levels. However, after the decline in the first quarter, the actual EU steel consumption is expected to stabilize near the beginning of the year for the rest of the year.Since the high price of iron ore and coking coal is expected to continue until the end of this year, all steel market participants are increasingly concerned about the full process steel production costs. In addition, iron ore supply pressure will continue until the end of the year. Trade protectionism has disrupted the global supply chain, and the protectionism of the steel market has complicated the global market situation. The 232-term steel import tariff that the United States began to implement in March 2018 has created a new wave of trade protectionism, which has caused the global steel supply chain to be affected by the trade war.

0 notes

glorysteelwork-blog · 6 years ago

Text

Microstructure and Mechanical Properties of S355 Steel Welded Joints

S355 steel sqaure bar

is a kind of low alloy high strength structural steel produced in accordance with European standards. S355 steel square bar has strict requirements on chemical composition, strength, plasticity and low temperature toughness. S355 steel square bar is widely used in electric power, construction, bridges, and pressure vessel welding structures, and is also used in railway vehicle manufacturing. At present, China is implementing the high-speed railway passenger transportation strategy, the train running speed is greatly improved, and the steering frame will bear a greater dynamic load. Therefore, higher requirements are placed on the mechanical properties of the welded components, and the performance of the welded joints directly affects the safety and reliability of high-speed railway passenger cars.The tensile test results of the front fillet weld cross joint of S355 steel square bar can be seen that the cross joint without gap and without gap and the cross joint with 45° K groove and without gap are stretched at the weld position. This indicates that under the test conditions, the room temperature shear strength of the welded joint of S355 steel is much higher than that of the base metal under static load conditions. The welding head without the groove can meet technical requirements. At the same time, it should be noted that the roots of the welded joints of these two types of joints have cracked. By observing the end faces of the eroded welds, it is found that the roots of the cross joints of the 45° K-shaped groove are not welded completely and become crack source, which eventually cracks at the root of the weld under tensile load. The welded joints are in the form of a bevel and a certain assembly clearance is an effective measure to avoid incomplete penetration. It is recommended that the welded joints be welded at the opening and leaving a gap to avoid incomplete penetration and sufficient strength. As for S355 steel welded joints, the weld structure is mainly a large number of coarse and strip-shaped pro-eutectoid ferrite precipitated along the original austenitic columnar grain boundary, close to the pro-eutectoid ferrite near a small amount of pearlite structure. The crystal is acicular ferrite, and the size is large, and there is a certain amount of granular bainite. The weld zone of the fusion zone and the superheat zone of the heat-affected zone is the weld metal, and the right side is the microstructure of the superheat zone. It can be seen that the grain size of the fusion zone and the superheat zone are different, mainly the block pro-analytic analysis along the grain boundary of the prior austenite. The heat affected zone structure is uniform bulk ferrite and pearlite, and the grains are very fine. The base material is uniform small piece of ferrite and pearlite. The microstructure of the weld depends on the welding material and welding procedure specifications. In engineering practice, the welding heat input should be strictly controlled to obtain more desirable mechanical properties.

0 notes

glorysteelwork-blog · 6 years ago

Text

Welding Process Analysis of S45C Steel and S235 Steel

S45C steel is a kind of very high quality carbon structural steel with good performance and process performance. S45C steel square bar is widely used in the machinery industry and is mainly used as mechanical parts such as shafts, gears and high strength bolts.

S45C steel square bar

is a kind of carbon structural steel with carbon content of 0.45%. S45C steel square bar belongs to medium carbon steel, and its mechanical properties are high in strength but poor in toughness. S45C steel square bar has less harmful impurities and non-metallic inclusions, stricter chemical composition control, better plasticity and toughness. S45C steel square bar is suitable for the manufacture of more important mechanical parts. S235 is a kind of common structural steel, belonging to engineering steel, mainly used for steel components, such as angle steel, channel steel, I-beam, steel plate and so on. S45C steel and S235 steel have good metal properties and a wide range of applications. The analysis of S45C steel and S235 welding processes and their weldability is of great significance in welding production. As a kind of medium carbon steel, S45C steel square bar has poor weldability and is prone to defects during the welding process. S235 steel has good welding performance because S235 steel is structural steel, which belongs to engineering steel and has low carbon content and it is a kind of good welding base material.The right process is the basic condition for quality assurance. Carbon dioxide gas shielded welding is an important welding method. Compared with other arc welding methods, it has stronger adaptability, higher efficiency, better economy and easier access to welded joints that meet the performance requirements. The carbon dioxide gas protection welding of S45C steel and S235 has strict environmental requirements, and it is required to be carried out in a windless environment. Once there is wind, there will be defects of pores, and although the speed of carbon dioxide gas protection welding is relatively fast, the welder’s level of operation is high. According to the chemical composition analysis of the base material S45C steel and S235 steel, the carbon equivalent of S45C steel is 0.63% from the viewpoint of carbon equivalent. The carbon equivalent is relatively large and the weldability is relatively poor. In order to avoid cracks after welding, it is necessary to preheat 250 °C before welding and 550 °C stress relief annealing after welding is also quite necessary. S235 has good weldability, but due to the characteristics of dissimilar steel welding, it is necessary to formulate welding process parameters according to S45C steel with poor weldability. The hardness distribution of the welded joint is as follows. The hardness of the heat-affected zone varies widely, and the hardness value is high. In particular, the fusion line has a high hardness value due to elemental diffusion, and the hardness distribution of the weld is relatively uniform.

0 notes

glorysteelwork-blog · 6 years ago

Text

Advantages of Rail Elastic Fastening Device in Steel Beam Rail

With the rapid development of social productivity, the speed of capital construction is accelerating, and the traditional frame-type industrial plants with concrete beam-column structure are gradually being replaced by steel structure factories. The lifting and transportation equipment is also becoming larger and more efficient， which has new requirements about

crane rail steel square bar

installations. The application of the crane rail steel square bar elastic fastening device in the installation of the steel beam rail can effectively reduce the looseness of the rail pressure plate, the deformation of the rail and the fracture caused by the increase of the wheel pressure of the lifting machine and the increase of the operating frequency, and can save the construction cost, which speed up the crane rail steel square bar installation.At present, the crane rail steel square bar in China generally adopts two kinds of pressure plate fixing methods, namely bolt pressing plate and rail press device. The bolt pressing device is the earliest used and the most widely used. The crane rail steel square bar is fixed by the two side pressing plates, and the pressing plate is fixed on the crane beam by bolts. Although this method has its advantages in the installation of concrete crane beam rails, it has great defects in the installation of crane rail steel square bar. The inclined iron block self-locking type rail press is an improved type of bolt pressing device. The lower cover plate is welded on the crane beam, and the upper and lower cover plates are connected by T-bolts, and the upper and lower cover plates are fixed by tightening the wedge iron, which solve the problem of drilling holes in steel beams, but there are also some defects.The rail elastic fastening device is composed of a Z-shaped fastener and an e-shaped elastic strip. The Z-shaped fasteners are welded on the upper wing of the steel crane beam to resist the horizontal force and the rail force of the crane. During welding process, the welding length can be designed as three-sided welding or two-side welding according to the horizontal lateral force of the wheel. Rail elastic fastening devices have the following advantages. The rail spring fastening device is fully elastically connected and can securely fasten the rail in vibration. The e-shaped spring bar and the Z-shaped fastener are spliced, and the inclined bottom surface of the rail is in contact with the pre-stressing stress. This will cause the spring bar to be pressed against the track forever, so that the stress is transmitted to the crane beam through the spring bar. When the crane rail steel square bar is installed, the correct pressing force is automatically generated. Different rail type rail elastic fastening devices have pre-set the corresponding pre-tightening force. There will be no flaking, corrosion or failure, which will prevent the platen from loosening due to the creep of the thread and exempt the maintenance inspectors from a lot of heavy work during use. The rail elastic fastening device consists of two simple components, it is easy to be installed and intuitive to be checked. It’s safe and reliable with long service life. It has the ability to resist longitudinal forces and resist lateral forces, reducing the rail breakage of the rail under the action of ambient temperature forces and the horizontal forces generated by the large wheels during operation. It can also weaken the damage of the crane lateral impact force and the crane rail force on the structure of the rail, the crane beam brake system and the column, thus prolonging the service life of the structure. There is no need to drill holes in the upper beam of the crane beam, which reduces the manufacturing cost of the beam and improves the manufacturing speed of the crane beam. The waveform ratio of the upper wing increases, and the cross-section strength of the beam is correspondingly increased. Through the positioning of the fastener, the accuracy of the rail installation (span, straightness) can be ensured, and the offset of the rail to the center of the crane beam can be reduced. The utility model effectively solves the phenomenon that the serpentine bending, improve the service life of the track and wheels, and ensure the smooth and safe operation of the crane. The e-shaped spring bar can be freely disassembled and reused, which can shorten the construction period of the track replacement and save construction costs. The application of the rail elastic fastening device can effectively improve the efficiency of engineering construction, reduce equipment accidents and daily inspection and maintenance workload, reduce the overall cost, and is highly praised by the construction unit and the use manufacturer in terms of practical and economic effects.

0 notes

glorysteelwork-blog · 6 years ago

Text

Light Steel Rail 60×40 Flat Bar Application in Cranes

At present, the common types of rails used for crane trolleys include QU70 rail, QU80 rail, QU90 rail, QU100 rail, 18KG/M, 24KG/M, 38KG/M, 43KG/M,

steel rail 60×40 flat bar

, etc. The first four types are crane rails. 38KG/M and 43KG/M are hot rolled rails for railway use. Glory Steel could offer steel rail 60×40 flat bar as crane rail. The trolley running rails of cranes with a lifting capacity of 20 tons or less are all light rails. It can be seen that the light rails are widely used on cranes, so the application of the light rails in the current standard on cranes is worth studying. steel rail 60×40 flat bar is also widely used as crane rails. Of course, counting the results of previous products for light rail selection is only an empirical reference. Whether the new light rail can be adapted or not has to be explained by data.We should mainly consider the bearing capacity of the wheel and the rail during the selection of wheels and rails. In the design and selection process of the wheel set and the rail, the main data is the allowable wheel pressure, followed by the maximum working wheel pressure and the maximum static wheel pressure. The usual calculation method for the allowable wheel pressure is calculated by point contact and calculated by line contact. Since the line contact is closer to the actual situation of the crane operation, the calculation is usually performed in accordance with the line contact. When the material of the wheel and the rail is clear, the working level of the mechanism and the running speed are unique, the allowable wheel pressure is only related to the wheel diameter and the effective contact length. The effective width of the new light rail 12KG/M rail is greater than that of the 24KG/M rail of the old light rail. The effective width of the new light rail 15KG/M rail is greater than that of the 18KG/M rail of the old light rail. The effective width of 22KG/M is larger. Not only that, the effective width of the 30KG/M rail of the new light rail is already greater than that of the 38KG/M and 43KG/M in the railway track. When the other conditions are the same, the allowable wheel pressure is proportional to the effective width of the wheel and the rail contact. The larger the effective length under the same conditions, the larger the allowable wheel pressure, so the effective width of the current standard light rail is far superior to old standard light rail. The trend of the data of the allowable wheel pressure is very close to the trend of the effective contact width. Therefore, from the perspective of the allowable wheel pressure, the new light rail is not only suitable for the track of the crane trolley, but also has better performance than the old light rail.Substituting old light rails or railway rails with new light rails will reduce the weight of the rails used and reduce costs. With the new light rail instead of the old light rail or rail track optimization combination, the diameter of the selected wheel set can be reduced to achieve cost reduction. When the diameter of the wheel is reduced, the reduction ratio of the reducer required by the mechanism is also reduced, which is equivalent to increasing the load carrying capacity of the reducer, so that the reducer also has the possibility of cost reduction by selecting a downshift. The accessories such as the pressure plate for the new light rail have space for cost reduction. After adopting the new light rail, the quality of the running track of the trolley is reduced, and the running mechanism and the steel structure of the crane also have the possibility of weight reduction, so there is still room for indirect cost reduction. Since the rails of the new light rail are thin, the allowable pressure of the rail itself is not as good as that of the old light rail and the rail. Therefore, it is necessary to consider the rail itself when the static load test or the calculation of low speed, low working system, maximum working wheel pressure, maximum static wheel pressure and allowable wheel pressure. Due to the light weight of the new light rail, the rigidity may be relatively weak. Therefore, when the analog design adopts the new light rail, the crushing stress of the small wheel pressure on the main web is reviewed for the off-track beam. For the normal rail box beam and the semi-offset rail beam, the local bending of the upper flange plate is calculated. In summary, the new light rail is not only suitable for the selection of cranes, but also the track material with excellent performance and high cost performance, which should be preferred in practical design and application.

0 notes

glorysteelwork-blog · 6 years ago

Text

Opportunity for China Steel Products in South Africa

Four years ago, according to the statistics of the South African National Industrial Development Corporation (IDC), South Africa’s steel production at that time could meet domestic consumption, but by 2020, even the most conservative forecast, consumption will reach 10 million tons, exceeding the crude steel output at that time. Glory Steel could offer

A36 hot rolled steel plate

. Four years later, the predictions of the South African National Industrial Development Corporation (IDC) have become a reality ahead of schedule, with South Africa’s annual steel demand reaching 10 million tons. The African and Chinese people need a community of destiny. This community of destiny is based on solid cooperative measures and deserves the common struggle of both sides. China-Africa relations have entered a golden age. This is an era of extraordinary significance and deep cooperation. The two sides are a mutually beneficial and win-win partnership. China’s relations with African countries are based on equality and mutual respect.At present, China’s steel industry is still in the period of supply-side structural reform. In 2017, China’s steel industry completed 50 million tons of de-capacity tasks. Green development is the steel production tendency for China in the future. South Africa is the first major force in Africa’s economic development. The economy and industrial base are good, and the steel demand is strong. It is understood that South Africa has experienced strong economic growth in recent years, especially in the mining, construction and communications industries. According to relevant statistics, as of 2016, South Africa’s per capita steel consumption was only 97.1 kg, far below the world average. According to data from the World Iron and Steel Association, South Africa’s steel demand is affected by the economy in 2017, but South Africa’s total steel consumption is still low, which means a broad development space. Among the downstream steel demand industries in South Africa, the demand for A36 hot rolled steel plate is larger in the manufacturing industries of automobiles, home appliances and electric wires, accounting for 54.8%. The automobile industry accounts for 6.4% of South Africa’s total GDP and 11.8% of total exports. The overall capacity of local steel companies in South Africa is low. It is understood that after years of development, South Africa has formed a relatively complete steel industry system, but the local steel enterprises’ overall production capacity is low. Among them, the largest production capacity is ArcelorMittal South Africa. The current crude steel production capacity is only 7.1 million tons. Other steel companies such as CISCO and Davsteel have a capacity of less than 1 million tons. The South African Employers’ Federation has more than 10,000 corporate members, more than 2,000 of which are in the steel industry. South Africa’s current steel demand is about 10 million tons. Besides the annual supply of 5 million tons of Mittal South Africa, there is still a demand gap of 5 million tons that needs to be filled by imports. South Africa has a demand for some steel products and steel sheets for construction. South Africa hope to seek cooperation opportunities with Chinese steel companies.South Africa has a huge steel market demand, and China steel market is overcapacity. It should be a win-win opportunity. But due to the vigilance of China’s steel exports, trade barriers between South Africa and China’s steel products have occurred frequently in the past few years. Although China-Africa cooperation is further deepening, trade frictions still exist. In order to curb the massive export of Chinese steel to South Africa, a 22% tariff is imposed on Chinese steel products. This is just the behavior of the state, as consumers do not want it. Despite the addition of tariffs, steel market demand still exists and cannot be blocked by human factors. This kind of government’s practice will not only affect the steel industry, but it will also affect South Africa’s steel downstream, such as automobiles and other manufacturing industries, which is extremely unwise. As long as the quality of our products is good enough and the price is favorable, trade protection can’t stop the market demand. Only by abandoning the idea of unilateral trade and strengthening cooperation can we achieve win-win cooperation.

0 notes

glorysteelwork-blog · 6 years ago

Text

Current Status and Analysis of Steel Rails after Heat Treatment

With the continuous development of high-speed and heavy-duty railways, the construction of seamless lines has become an important part of railway development, and the welding joints of the

steel rail flat bar

are related to the key aspects of seamless line quality. Therefore, at present, domestic and foreign railway construction units and related management departments have strictly controlled the quality of the rail welding process, and have also adopted corresponding post-weld treatment measures to ensure the quality of the on-line

steel rail flat bar

welded joints. Among them, an important means for improving the internal structure of the welded joint during post-weld heat treatment can eliminate the superheating zone near the fusion line, refine the grain, improve the weld strength and toughness. In the construction of railways in China, post-weld heat treatment of steel rail flat bar is an indispensable part. Flash welding and gas welding heads must be heat treated after welding, including normalizing and any process measures to increase or decrease the cooling rate of the welded joint. Generally, the fixed flash joints in the welding steel rail flat bar factory are mostly heated by medium frequency electric induction, and then subjected to normalizing treatment by means of forced air cooling. The on-site moving flash welding head and the air pressure welding head are limited by the construction environment and equipment conditions, and are often heated by a gas pressure welding heater flame swing method, and then normalized in a natural cooling manner during the construction period. With the advancement of technology, mobile medium frequency electric induction and heating equipment for on-site flash welding and air-welding head heat treatment have also been successfully developed, and satisfactory test results have been obtained.The electric induction heating equipment used for post-weld heat treatment of steel rail flat bar is mostly medium frequency inverter induction heating equipment, including power supply, intermediate frequency power supply, water cooling system, compensation capacitor, intermediate frequency transformer, heater, air spray (spray) cooling device and data acquisition and Management system and other parts. The production process of steel rail flat bar heat treatment after welding with medium frequency electric induction heating method should be controlled from heating start temperature, maximum heating temperature, heating time, heating power, frequency, DC voltage, DC current, air injection starting temperature, air blowing end temperature, wind pressure, joint heat uniformity, and other parameters by. The steel rail flat bar material is mostly high carbon steel in the hypoeutectoid steel, and the normalizing heat treatment temperature is usually from 820 °C to 840 °C, and after a period of heat preservation, it is cooled to room temperature in air or forced flow of air. However, there is no heating and post-heating device for the base and on-site rail welding. Only the method of instantaneous overheating can promote the full transformation of the internal structure of the rail joint. Therefore, the maximum heating temperature of the rail head is required to be controlled between 850 °C and 950 °C. In addition, since the normalizing temperature is too high, the grain will continue to grow and the quality requirements of the relevant standards cannot be met. Therefore, the normalizing temperature should be lower than 500 °C.

0 notes

glorysteelwork-blog · 6 years ago

Text

Asian Steel Trade Faces Multiple Challenges

Weak domestic demand and trade friction are important challenges facing the development of the current steel industry, and the abuse of trade protection measures is bringing many negative effects. Hot rolled steel plate is one of main products of Glory Steel Company. At present, the biggest problem faced in the Korean steel industry is that steel consumption has stagnated. Besides the poor performance of downstream industries such as domestic appliances, automobiles and ships, which restricts steel demand growth. The trade restrictions adopted by the United States have also caused a significant drop in the export of steel products to the US market this year. This poses more challenges for Korean steel companies that expect to export their digestion capacity. At the same time, due to insufficient domestic demand and export volatility, South Korea’s imports of steel products from Japan and China are also decreasing this year.Steel consumption in Taiwan is mainly for the construction, manufacturing and export of the island. Demand for steel in construction and manufacturing has been saturated and has been slowly declining over the past 20 years, and new production in the later stages need exports to digest. Taiwan’s steel exports are mainly galvanized coils,

hot rolled steel plate

and cold rolled steel plate. Faced with the challenges of current industrial structure, steel trade barriers and strong environmental protection requirements, the steel industry structure needs integration and upgrade. We should produce innovative materials, add process technology processing and design to increase the added value of products, enhance competitiveness, and strengthen the exchanges with the industry in various regions to jointly prevent the occurrence and upgrading of trade friction.Indonesia’s economic growth is relatively good. Steel demand is expected to remain at a high level, and the current low per capita consumption of steel in Indonesia also indicates that it has huge market potential. In view of the growing domestic demand, some steel companies want to increase production capacity. However, there are almost no upstream plate suppliers in Indonesia, and local billet demand is more dependent on imports. At the same time, the supply and demand gap of many steel products is large, and it needs to be supplemented by imports. This has provided more trading opportunities for the market.For the development of China’s steel market, this year, the normalization of environmental protection and production limits have led to a year-on-year decline in steel production. The strong resilience of China’s economy has ensured the smooth operation of domestic steel consumption, making the overall spot price of China’s steel stock market at a high level. Profits remain high. The Chinese government believes that we should focus on four aspects, namely environmental protection, demand, trade friction, and capacity. In the past three years, China has basically completed the task of de-capacity of 150 million tons of hot rolled steel plates. In the future, it will mainly control steel production capacity through reduction and replacement. However, as China’s environmental protection continues to increase, the environmental protection of the steel industry will become the norm. On the demand side, there are signs of weak demand in China’s major downstream industries. At the same time, the trade friction between China and US may also indirectly affect China’s steel demand.Data show that since 2016, China’s steel exports have continued to decline, but this year’s export prices have an upward trend. In this context, the stability of the trade order in the Asia-Pacific region is critical to the global market. To this end, China, Japan and South Korea should adhere to the principle of openness and fairness, maintain trade order, jointly deal with the abuse of rules to excessively protect the market, and safeguard the hard-won stable development of the global steel market.

0 notes

glorysteelwork-blog · 6 years ago

Text

Determination of Rail Material and Heat Treatment Process

The

steel rail square bar

material usually has metal carbon content of 0.68% and 0.80%, which is a kind high-carbon steel in the sub-eutectoid steel. After heating the metal of this component, the crystal grows rapidly. When it’s heated to the welding temperature, it is basically in the first-order crystal particle size, belonging to the austenitic superheated structure. It is preserved under the condition of rapid cooling in the air after welding and extinguishing. The coarse-grained austenite structure is characterized by low plasticity, toughness and strength, hard and brittle, and cannot be used in the actual application. The coarse-grained austenite structure must be eliminated by heat treatment. For the hypoeutectoid steel, the most suitable treatment method is complete annealing. It not only refines the grains, uniformizes the structure, but also improves the strength, plasticity, toughness and hardness. It also eliminates the internal stress, but it takes long time and the necessary equipment. It is difficult to implement in the appearance field. With normalization, the pearlite structure can be also obtained, but the grain is finer and the dispersion is larger. In addition, the strength, toughness, impact resistance by normalization are higher than the microstructure obtained by annealing, and the process is simple, the time is short, the equipment is simple, and it is convenient for on-site construction.The specific normalizing process is as follows. After the tumor is removed, the weld line is immediately normalized when it is cooled between 400℃ and 500 ° C. If it is prematurely normalized, the core temperature of the steel rail square bar is still high, and there will be tendency for the crystal grains to continue to grow. However, if the normalizing fire is too late and there will be possibility that the normalizing fire does not completely leave the coarse crystal nucleus, it will affect the performance of use and will not achieve the purpose of normalizing. Normalizing after the steel rail square bar welding with welding heater, the flame uses weak carbonized flame, which can reduce the combustion ratio or reduce the gas supply. This kind of flame is soft, the heating time is longer, and the organization is better. The gas-welded steel rail square bar joint has a normalizing temperature between 870℃ and 920°C or between 850℃ and 900°C. When the steel rail square bar temperature rises to this temperature, the flame is extinguished and allowed to cool naturally in the air. For steel rail square bar with high carbon content, we should use a lower heating temperature and use a higher temperature for the steel rail square bar with lower carbon content. It has been proved that the post-weld heat treatment of the steel rail square bar adopts the above two-stage normalizing process, the grain size is stable from grade 7 to grade 8, and various mechanical properties are also ideal.The steel rail square bar post-weld heat treatment equipment is mainly composed of a heater, a gas flow control box and an automatic swaying machine. The components can be coordinated and organically connected to jointly realize the post-weld heat treatment process requirements of the steel rail square bar. The heater is a heating device for heat-treating the steel rail square bar. The flame is an oxy-acetylene flame. The structure is a split-type single-mixing chamber heater. The heater contains a pneumatic system and a waterway system. The cycle takes forced water cooling.

0 notes

glorysteelwork-blog · 6 years ago

Text

Increased Steel Production in Vietnam May Affect Global Market

Due to the strong export performance of Vietnam’s

hot rolled steel coil

products and the increase in domestic production, it is expected to affect the global hot rolled steel coil trade pattern in 2019.Although steel exports are affected by the US 232 tariffs, unlike other Asian countries, the volume of exports to the United States has increased significantly in 2018.According to the US Census Bureau, Vietnam exported 1.11 million tons of steel to the United States in 2018, a 48% increase from 2017. Last year, US steel imports totaled 25.69 million tons, of which imports from Vietnam accounted for about 4.3%. One of the reasons for the increase in Vietnam’s steel exports is the increase in production at Formosa Ha Tinh Steel Corp. On May 18, 2015, the company’s second blast furnace was put into operation, doubling its crude steel capacity to 7 million tons. Formosa Plastics holds a 70% stake in Formosa Plastics, and Sinosteel and JFE Steel hold 20% and 5% respectively. Although US steel imports fell by 13.1% year-on-year to 25.69 million tons in 2018, imports from Vietnam accounted for a significant increase from 2.5% (about 749,000 tons) in 2017.In 2018, Vietnam’s steel exports amounted to 6.26 million tons, an increase of 33% from the figure of 4.71 million tons in 2017. In the same period, the country’s steel imports were 13.5 million tons, down about 10% from 15 million tons in 2017. According to data from the Vietnam Iron and Steel Association, Vietnam’s steel imports and exports have a reverse year-on-year trend, mainly due to a 14.9% year-on-year increase in Vietnam’s steel output to 24.19 million tons.Data show that Vietnam’s hot rolled steel coil production increased the most, last year, to 3.44 million tons, nearly 1.5 times more than the 1.38 million tons in 2017.According to market sources, in the first quarter of 2019, Vietnam’s largest steelmaker, Hoa Phat Group is expected to maintain steel production. The company plans to complete the construction of the Dung Quat steel plant by the end of this year and gradually put all four blast furnaces in the plant into production. The mill’s design capacity for crude steel is 4 million tons per year, half of which will be used to produce hot rolled coils.On March 7, a report from the Vietnam Steel Industry released by Citi Research showed that when judging global steel production trends, it is necessary to pay attention to the growth of countries that are not traditional producers but may change the balance of global steel trade.

0 notes