Method for resistance welding with pre-chilling

A method for improving the resistance spot welding of two or more stacked metal sheets, comprising:

• providing the metal stack;
• positioning first and second opposed electrodes on opposite sides of the metal stack;
• flowing chilled gas onto the outer surface of the metal stack to cool a region where a weld is to be made;
• and applying weld current to the first and second electrodes and through the metal stack to create an electric resistance spot weld between the stacked metal sheets after chilling of the outer surface has lowered the temperature at a faying interface between the stacked metal sheets.

A method for improving the resistance spot welding of two or more stacked metal sheets, comprising:

• providing the metal stack, at least one of the metal sheets of the metal stack having different thickness or material from another of the metal sheets;
• positioning first and second opposed electrodes on opposite sides of the metal stack;
• operating one or more valves to flow chilled gas onto a surface of the metal stack to cool a region where a weld is to be made and obtain a lowering of the temperature at the faying interface between the metal sheets of at least 5 degrees Celsius;
• and applying weld current to the first and second electrodes and through the metal stack to create an electric resistance spot weld between the metal sheets only after the lowering of the temperature at the faying interface between the first and second metal sheets by at least 5 degrees Celsius.