Four of the main characteristics that metallurgists keep in mind when welding stainless steels are a lower melting temperature, a lower coefficient of thermal conductivity, a higher coefficient of thermal expansion and higher electrical resistance in comparison with most carbon steels. Stainless steel welding experts often use a heat sink made of aluminum or brass, clamping the piece behind the seam of the weld to absorb heat and prevent burn through.
In general, stainless steel welders use as little heat as possible, particularly when working with thin material. When performing shielded metal arc welding, stainless steel welders typically choose between two basic types of electrode coatings: a titanium-type coating and a lime-type coating. Lime-type coatings carry a reverse polarity, while titanium-type coatings are suitable for use with positive direct current or alternating current. Generally, the titanium-type coating offers more appeal to welders.
Stainless steel welders commonly use tungsten arc welding for thin sections of stainless steel. Argon provides gas shielding, although automatic applications may use a mixture of argon and helium.
Gas metal arc welding is faster than most other types of welding techniques. For this reason, welders usually use it for thicker materials.