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What is D2 steel

D2 steel is an alloy tool steel. It is rich in superhard alloy charcoal, so it has high wear resistance, good toughness, impact resistance and high gold content. Therefore, it has good resistance to softening at high temperature and can be carbonized after hardening.

D2 steel always is used to make cold acting die steel, rolling, punching die, circular shearing blade, deep oil die, plastic mold with high wear resistance.

Then according to the required performance tempering, low temperature tempering 100~250 degrees, HRC61~63, suitable for high hardness, high toughness object high temperature 500~550 tempering 3 times, HRC58~62, after tempering at 400~ Used in the 550 degree range, the mold does not reduce the hardness and is suitable for high hardness objects used at this temperature.

Carbon(C): 1.50%-1.68%: Helps to increase hardness, blade sharpness retention, tensile strength and abrasion resistance.

Chromium(Cr): 11.50%-12.00%: Helps to improve strength, wear resistance and corrosion resistance.

Molybdenum(Mo): 0.60%-0.90%: Helps improve workability, corrosion resistance and high-temperature strength.

Vanadium(V): 0.90%-1.10%: It can refine grains and improve toughness and blade sharpness retention.

Manganese(Mn): 0.15%-0.45%: Helps to improve strength, wearing resistance and grain structure.

Silicon(Si): 0.10%-0.40%: Helps increase strength.

Phosphorus(P): Max 0.03%: A small increase in strength and hardness.

Sulfur(S): Max 0.03%: Improve workability.

Iron(Fe) is a component of balanced steel.

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The Overpass

The overpass is a bridge. Mainly refers to a series of narrow reinforced concrete or masonry arches. It has towers or pillars that are highly supported. A bridge that spans valleys, rivers, roads, or other low-altitude obstacles. Due to the development of the city, the traffic is crowded, the buildings are dense, and the streets are difficult to widen. Therefore, with this type of bridge, traffic density can be dredged, and the transport rate is mentioned.

The sharp increase in the urban population has led to an increase in vehicles, and the crossing of the plane interchange has caused traffic jams and congestion. It is necessary to form a multi-layered three-dimensional layout by repairing the bridge and the elevated road to improve the speed and passing ability. The connection between the urban ring road and the expressway network must also be diverted and guided through large-scale interchanges to ensure smooth traffic. Urban overpasses have become an important symbol of modern cities. Bridges built at the intersection of roads and railways to ensure that traffic does not interfere with each other. Widely used in busy traffic on highways and urban roads. Mainly divided into two categories. One of them is a flyover. Cross over existing lines. It is divided into separate and interactive. The former only guarantees that the vehicles on the upper and lower lines are independent of each other. The latter enables vehicles on the upper and lower lines to pass each other. The construction of complex roundabouts on planes and façades takes up a lot of lands. To reduce noise, prestressed concrete bridges are often used. The other is an underground bridge. Cross the existing route from the ground. Consisting of bridge holes, approach roads and subsidiary structures. When constructing, underground pipelines need to be demolished, and the amount of auxiliary works is large. This is far less than building a flyover economy. And design should pay attention to the requirements of clearance, ventilation, lighting, drainage and cold areas.

The arrangement and form of the piers of the urban elevated line bridges directly affect the traffic and aesthetics. Column, pile, rigid frame and thin-walled piers are often used. When designing urban rail transit viaducts, the impact on the landscape should be considered first. While considering the structural requirements and strength requirements of the structure itself, it should pay attention to the artistic shape of the bridge. Put the beautification design of the structure in a prominent position and try to integrate with the surrounding environment. The structural shape and the size ratio of each part should be coordinated with each other. The beam structure is stretched smoothly, paying attention to its line type. The lower structure is simple and light, and the permeability is good, making the viaduct a beautiful landscape of the city.

Today, the world’s first overpass is the Beipanjiang Bridge. And the 4140 steel is the popular material for that. It is in China. The bridge spans the Beipanjiang Grand Canyon at the junction of Yunnan and Guizhou provinces. With a total length of 1341.4 meters, the bridge deck reaches a vertical height of 565 meters, making it the world's tallest bridge.

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the Eiffel Tower

As we all know, the Eiffel Tower is a famous building in the world that everybody knows. The Eiffel Tower is one of the symbols of Paris. It is called "Iron Lady" by the French. It is known as the three famous buildings in the West, together with the Empire State Building in New York and the TV Tower in Tokyo. In 1889, the 100th anniversary of the French Revolution, a large international fair was held in Paris to celebrate. The most eye-catching exhibit at the fair is the Eiffel Tower. It became a symbol of the industrial revolution that swept the world at the time.

The designer of the Eiffel Tower is the French architect Gustave Eiffel. In his early years, he was known as the Garabit viaduct expert. He has many masterpieces all over the world in his life. But what made him famous is the tower named after him. In the beginning, the French government decided to build the tallest tower in the world in Paris. But the funds provided are only one-fifth of the cost. To realize his design, Eiffel once mortgaged his construction company and all his properties to the bank as an engineering investment.  On January 28, 1887, the Eiffel Tower officially started construction.

There are 250 workers, working 8 hours a day in winter and 13 hours a day in summer. Finally, on March 31, 1889, the tower of the steel structure was completed. The Eiffel Tower has more than 18,000 metal parts and weighs 7,000 tons. During the construction, a total of 7 million holes were drilled and 2.5 million rivets were used. Since each part on the tower was strictly numbered in advance, there was no mistake in assembly. The construction was carried out in full accordance with the design, and no changes were made in the middle. It can be seen that the design is reasonable and accurate. According to statistics, there are more than 5,300 design sketches of the tower alone, including 1,700 full maps. The completed Eiffel Tower was 300 meters high until 1930 when it was the tallest building in the world. Today, radio and television antennas have been added to the tower, which has a total height of 320 meters.

Eiffel Tower is a steel frame hollow structure. It is 324 meters high and weighs 10,000 tons. He has three-story platforms of 57 meters, 115 meters and 274 meters above sea level for excursions. The fourth-floor platform is 300 meters above sea level and has a weather station. The top has an antenna and is the Paris TV Center. From the ground to the top of the tower is an elevator and 1,710 steps. The tower has an interlaced structure. It consists of four large, concrete-built iron columns with a 75-degree angle to the ground. The tower is equipped with four hydraulic lifts. It uses more than 1,500 giant beams, 1.5 million rivets, 12,000 steel castings, and a total weight of 7,000 tons. It took 17 months for 250 workers to build and the cost was 7.4 million gold francs. The tower paints every 7 years, using 52 tons of paint each time.

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Stainless steel

Today, stainless steel is widely used as a health material and covers almost all areas of human health. The stainless steel water pipe has the advantages of being fully recyclable, saving water resources, reducing transportation costs, reducing heat loss, and avoiding pollution. Stainless steel is the abbreviation of stainless acid-resistant steel. Among them, the resistance to air, steam, water and other weak corrosive media or stainless steel is called stainless steel. The steel grade that corrodes chemically resistant media is called acid-resistant steel.

Their corrosion resistance is different due to differences in chemical composition between the two. Normal stainless steel is generally not resistant to chemical media corrosion. And acid-resistant steels generally have rust properties. The term "stainless steel" refers not only to a type of stainless steel but to more than one hundred industrial stainless steel. Stainless steel is often divided into martensitic steel, ferritic steel, austenitic steel, duplex stainless steel and precipitation hardened stainless steel. Besides, it can be divided into chromium stainless steel, chrome nickel stainless steel and chromium manganese nitrogen stainless steel.

Among the many stainless steel types, 304 stainless steel is currently the most popular. 304 stainless steel is common stainless steel. It is a versatile stainless steel material with high rust resistance and high-temperature resistance. It generally uses a temperature limit of less than 650 °C. It also has excellent stainless corrosion resistance and good resistance to intergranular corrosion. It has good corrosion resistance to alkali solutions and organic and inorganic acids. Its thermal expansion properties and thermal insulation properties are excellent. The most important point is that 304 stainless steel is affordable. 304 stainless steel is widely used in household appliances (cabinet, indoor pipeline, water heater, bathtub), auto parts, medical equipment, building materials, chemicals, food industry, agriculture, ship parts, etc.

304 stainless steel has many advantages. It is an environmental guardian. Eliminate the problem of red water, blue-green water and hidden water, no odor, no harmful substances precipitated to keep the water pure. And lead-free is not harmful to human health. Its surface is beautiful and clean. Long-lasting and scratch-free, never rust and never break. It is resistant to low temperatures. The kitchen bathroom stainless steel water pipe, faucet angle valve will never break. Finally, his thermal expansion properties and thermal insulation properties are excellent. It is not only certified by the authority but most importantly it is affordable in the market.

But stainless steel also has some problems. Stainless steel is a very thin, strong and dense, stable chromium-rich oxide film formed on its surface. This film prevents the oxygen atoms from continuing to infiltrate and continues to oxidize to obtain corrosion resistance. Once there is a reason for this, the film is continuously destroyed, and the oxygen atoms in the air or liquid are continuously separated to form loose iron oxide, and the metal surface is continuously rusted. The reason why stainless steel can be stainless is because of the presence of chromium and nickel. Lowering the content of these two components will reduce rust prevention performance. So this is critical in the production process.