Can mild steel be welded to stainless steel?
If you mean carbon steel yes. It is frequently welded with carbon steel. The factors to consider when welding two different metals together are:
mechanical and physical properties of the welded joint in the intended service;
proper filler metal selection; and
proper welding process selection.
Austenitic, martensitic and ferritic stainless steels can be readily welded to carbon steel using a filler metal that can tolerate the dilution by both base metals without formation of flaws in the joint. Typically an austenitic stainless steel or nickel alloy filler metal is used. The actual selection of filler metal and welding process would depend on the application and service conditions of the finished joint.