Spot welding of different metals-Stainless steel

Stainless steel is having lower thermal conductivity compared to mild steel. Therefore, it requires less heat input. But, stainless steel losses about 50 % its tensile strength if heated above 700 - 800 °C and if it is maintained at this temperature for more than an extremely short duration, this material losses its corrosion resisting properties. From these factors, the following requirements can be derived for spot welding of stainless steels:

• Short welding time in order to limit the area of metal heated.
• Very good cooling.
• Increase in mechanical and electrical power input by 50 % to 100 %.