weldingexpert-blog

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Welding steel beams - what do you have to pay attention to?

Welding is the type of connection for all steel components. However, what you have to pay particular attention to when welding steel beams, and what special rules apply to welding, read in detail in this article.

Weldability of steel

Not every steel is easy to weld. This also applies to steel beams. Although steel grades with a good sweat tendency are generally used for the production of steel beams, there may be some restrictions in individual cases.

To be on the safe side, you should look up the corresponding grade of steel on the basis of the material number in order to be able to check for existing restrictions for the respective steel grade. To know more about welding you can check weldersmen.

Basic requirements for weldability

Basically, the weldability of steels is determined by the carbon content and the so-called carbon equivalent. To obtain the carbon equivalent, all-alloy components are weighted and added accordingly. The value that comes out has the same predictive value about weldability as the carbon content of mild steel.

Basically, the limit for good weldability is without restrictions at a carbon content (or carbon equivalent) of 0.22%. Welding is usually still possible up to a carbon content of around 0.3%, but preheated or low-stress annealing must be used. In addition, welding is only possible with restrictions and high preparation.

Restrictions on galvanized steel beams

Galvanized steel beams must not be welded if used for load-bearing structures! This is inadmissible according to the DIN because the load capacity can be affected.

Basic requirements for the welding of galvanized beams

Since the zinc layer provides protection against corrosion of the carrier, special measures are necessary before welding:

the zinc coating must be completely sanded off at the weld before welding (otherwise there is a risk of corrosion at the weld)

the corrosion protection must be fully restored after welding at the welding point (this is also regulated by DIN)

When abrading the zinc layer, no part of the substrate may come into contact with iron-containing grinding chips (also the risk of corrosion)

For the restoration of the zinc layer after welding zinc paste and zinc sprays are suitable.

TIPS & TRICKS

For welding low alloyed or unalloyed steels, MAG welding, an arc welding process, is in many cases quite a viable process suitable for many applications.

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Welding steel - what should you pay attention to?

The image of a welding worker seems to be a typical image for the metalworking industry. But can you weld any steel at all? And what do you have to pay attention to? Which welding processes are suitable for steel at all? Answers can be found in this post.

Requirements for welding

By no means, all steels are weldable at all. This is always dependent on the respective alloy and thus on the steel grade. What properties steel has in terms of weldability, you will learn exactly when looking under the respective material number in a directory.

Basic rule: carbon content

The most important measure of the weldability of steel is carbon content. Steels are defined as alloys whose main constituent is iron and whose carbon content is less than 2.06%.

However, only steels with a carbon content of less than 0.22% are weldable. With a carbon content of between 0.22% and 0.3%, many sheets of steel can still be conditionally welded by doing some extra work to increase weldability (such as preheating or stress relief annealing).

Other elements

In addition to carbon, however, other elements in the alloy can influence the weldability. The higher the proportion of other elements (except iron and carbon) in the alloy, the more problematic the welding usually is.

To detect whether steel is basically still weldable serves the so-called carbon equivalent. Here, with different calculations, the mass percentages of the non-iron elements in the alloy are converted and added to the existing carbon in the alloy. The determined total value then indicates - depending on whether it is above or below 0.22% - whether one can still weld steel in principle.

Welding process for steel

As most suitable for many unalloyed steel grades but also stainless steel, the so-called MAG welding has proven. It is an arc welding process using active gases. The gases are used:

argon

Carbon dioxide and

oxygen

The ratio of the gases to each other is in each case adapted to the material to be welded.

Advantages of MAG welding

no burn-in

no spraying

no oxidation (if used indoors)

fast sweat progress

also applicable for unfavorable areas and in difficult positions

the high strength of the weld (called MAG weld welding bead)

TIPS & TRICKS

Even with fundamentally suitable low-carbon steels, there may be certain limitations with regard to welding (due to the particular alloy or the technical properties of the steel grade). Before welding, you should always look up the respective material under the material number.

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How to weld bronze?

If you want to weld bronze, you should consider the properties and special features of copper and copper alloys when joining. Below we have put together for you how to weld bronze and what to pay attention to.

Bronze is a copper alloy

Bronze is an alloy that has been known to humanity for many thousands of years. Although there are different bronze alloys, so also different base metals, which consist of bronze. But always included is a minimum share of 60 percent copper. As a result, bronze has similar welding properties to copper or other copper alloys.

Thus, the welding properties of non-ferrous metals have to be considered

As a non-ferrous metal alloy, bronze is therefore generally easy to weld. However, during welding, the copper absorbs atmospheric gases. This results in a negative effect on the quality of quality compared to the starting alloy. As a result, inert gas welding techniques are preferable to be used, ie TIG or MIG welding. This protects the molten bath for air.

In addition, it is difficult to achieve the necessary welding or melting temperature, since copper and thus bronze has a high thermal conductivity. As a result, a lot of heat is dissipated quickly and is no longer available for the process of melting. The phases have a special influence. Single-phase copper alloys are very good at welding, but multiphase alloys are only limited. Stay (Pb), for example, forms its own phase.

Welding process for bronze (copper alloys)

When welding so must be distinguished according to the different bronze alloys. Otherwise, the following welding methods are basically possible, whereby they are no longer used equally intensively:

Gas welding such as gas welding

Arc welding such as electric welding with electrode from welding filler

Inert gas welding with inert gases (TIG and MIG welding)

With craftsmen and thus also with do-it-yourselfers above all the shielding gas welding techniques are of importance. Electric and gas welding play only a minor role. However, preheating is usually essential because of high thermal conductivity.

Electric conductivity

Copper alloys are also less electrically conductive than pure copper and therefore better to weld. For alloys containing copper, the weldability is extremely limited. From 0.03 percent lead content, heat cracks are hard to avoid.

Flux when welding bronze

Basically, the use of flux is recommended for all copper alloys (except the MIG welding process). However, it should be noted that CuAl alloys (aluminum bronzes) require different fluxes. In addition, you must differentiate in the present copper alloy after the cold workability (copper Berrylium or copper-silicon would be cold deformable).

It must be distinguished after each bronze alloy

Copper-tin alloys are probably the most common home-made copper alloys (tin bronze) for welding. Again, the specific welding properties must be adapted to the metals contained beyond. This applies, for example, to CuSnPb alloys (copper tin-lead). In particular, MIG and TIG welding is considered to be best practice today (outside of industrial applications).

Important standards for welding bronze and copper alloys

In addition to the welding processes, which must be adapted to the existing alloy, the compositions of the weld additives are also important. You should be familiar with the numerous standards. These include the following standards:

CEN / TS 13388: 2008: Overview and composition of copper and copper alloy products

DIN EN 1982: Copper and copper alloys

DIN 8552-3: Weld preparation, joint shapes for copper and copper alloys, gas welding and arc welding

DIN ISO 15614: Gas welding and arc welding of copper and copper alloys (Part 6)

Of course, there are also all standards (DIN, ISO DIN EN, etc.) that are fundamentally important for welding processes and welding consumables.

TIPS & TRICKS

After welding, of course, the bronze has to be processed further. Among other things, the grinding and polishing of bronze are important. In addition, there are of course other methods of joining. Like the brazing and brazing of bronze.