To get the welding job done appropriately, you first need to acquire the knowledge of the metals that are suitable for welding. Different types of metals react differently to heat and the way they are manipulated. When the metals are heated, they tend to expand and become soft, and then it is determined how they would be applied and used. Metals also tend to react differently to the various type of welding methods. So before you go ahead to weld any metal, learn about the types of metal that are suitable for welding. Melting point, ductility, electrical conductivity and strengths are some points that should be considered when selecting a metal for welding.
Steel is a metal whose strength is known to the welders. Different type of steel requires a different type of heating and welding. Steel is an alloy metal which builds of iron and 2% of other metal elements. The most common type is carbon steel that can be found in the variations of high, low and medium. Higher the amount of carbon in steel stronger the metal becomes. Steel is a versatile metal that can be welded with any welding process. But due to oxidation, the steel still can get rusted and flake.
Here we provide you with additional information on the types of steel used for welding:
- Low Carbon Steel
Low carbon steel is easily weldable because as stated before, the steel with high carbon content is stronger. So low-content carbon steel is highly ductile as it contains less than 0.3% of carbon and up to 0.4% of manganese. Highly ductile means steel can be welded more easily. This reduces the chances of bitterness in structure and also eliminates the risk of hydrogen cracking. Low carbon steel is one of the best metals for welding and it can be welded using any equipment.
- Stainless Steel
Stainless steel is intendedly made to resist corrosion on the metal and stay clean. This is achieved by adding 10% to 30% chromium to other components in the steel like iron. The steel is weldable based on its grade. Ferritic and austenitic is the type of stainless steels that can be welded easily; martensitic steel is hard to weld and tend to crack. The stainless steel can also warp under the heat affecting the shape and size of the final piece. The chromium in the stainless steel will combine with the carbon during the welding process and the metal would become vulnerable to rust because of the lack of chromium oxide protective layer. You can prevent the damage by keeping the temperature as recommended.
Aluminium is similar to stainless steel. It is non-corrosive as compared to other metals. The aluminium is lighter than stainless steel, and for welding, pure aluminium and aluminium alloys are used. The aluminium requires oxide-free and high-power welding. Also, the welding differs for different grades as some are easy and some are difficult to weld. Aluminium has high thermal conductivity, and due to it, the heat is transferred from the weld on aluminium quickly. Equipment with high welding current should be used to supply the required heat to the aluminium. When the aluminium is cooling, it shrinks more than steel, so required measures should be taken to prevent any cracks or crates. Aluminium will have a coating of natural oxide on the base, which can add contaminants, so you should clean the aluminium and remove the coating to prevent any porosity during welding.
Among all the welding metals, copper is popular because of its heat conductivity, electrical conductivity, corrosion and wear resistance, and appearance. The metal is considered as "copper" only when it consists of 99.3% of copper. Arc welding is used to join copper and copper alloy. The intensity of the arc needs to be maintained during the welding process for copper and copper alloy to complete the fusion with minimum heating of the surrounding base metal. Whenever welding the copper and its alloys, you should use the flat position because the copper’s nature is highly fluid during the welding process. Copper should be preheated before welding and alloy copper should not be preheated because of the high thermal conductivity levels. To remove the oxides after welding, the copper should be cleaned with wire bronze brush from the welded areas.
The welding of nickel is performed using different nickel alloys that are available. The welding process for nickel alloy is similar to that of welding carbon steel. In some cases, oxyacetylene is preferred by the welders for the metal arc process. This is used when welding is done on thin wall pipes, tubing and tin gauge strip because the arc can penetrate that material. The welding style is also referred to use for high carbon steels due to the lower weld hardening result. The surface should be cleansed by removing all the oil, dirt and residue. Cleaned and greased metal will look like a shiny gold colour.
Magnesium alloys are lighter in weight, even lighter than aluminium. The magnesium alloy absorbs the vibration and they are easy to cast. The magnesium alloy is welded in a similar way as aluminium because both the metals have the same melting point. The magnesium alloy is welded with a TIG welding process. When the magnesium is grinding the shavings coming out would be flammable, and you should remember do not use water to put out the flames.
All the metals that are stated above are best for welding. So now as you know about different metals and their reaction to welding, you can choose the one that suits your need the best.