Group C material is a designation of the Resistance Welding Manufacturers Alliance (RWMA). It describes a group of Specialty materials with high strength and high electrical conductivity. Their properties make them excellent materials to use in the resistance welding industry as electrodes especially for galvanized steel.
RWMA has subdivided Group C. Currently it is represented by one Class 20 material. The product description, properties and applications of Class 20 can be found in the Resistance Welding Manual available through RWMA/AWS in section 18-3.