Steel is a metal alloy that primarily consists of iron and has a carbon content between 0.2 and 2.04 percent. It becomes harder and stronger but more brittle as the carbon increases, and other elements also affect its physical properties. The composition of the steel must be determined before it can be welded effectively.
Determine the weldability of the steel. This quality is inversely proportional to the steel's ability to be hardened by heat, also known as hardenability. Generally, this means that steels with fewer alloying agents are more weldable.
Measure the equivalent carbon content of different alloys of steel. This measure compares the properties of any steel alloy to those found in plain carbon steel. Carbon has the greatest effect on steel's weldability, followed by elements such as chromium and vanadium. Copper and nickel have the least effect.
Use high strength, low-alloy steel specifically developed for welding applications, if possible. There is always a trade-off between strength and weldability.
Weld stainless steels with greater difficulty. Austenitic grades of stainless steels are the most weldable, but they are particularly prone to distortion because of the high thermal expansion. Control the amount of ferrite in the weld to minimize any hot cracking with this type of steel. Use an electrode that deposits a weld metal with a small amount of ferrite.
Preheat and use special electrodes to weld other types of stainless steels.