PURPOSE: To prevent the cracking of solder at the time of soldering parts by subjecting karat gold to final heat treatment in an inert atmosphere at a specified temp. before final working and then carrying out slow cooling.

CONSTITUTION: Cu-contg. 9-to 22-karat gold is subjected to final heat treatment in an inert atmosphere at 400-700°C before final working into a product shape and then slow cooling is carried out by air cooling, furnace cooling or other method. The final heat treatment temp. may be regulated to 400-550°C. The workability is maintained and final working is satisfactorily carried out. The Au-Cu alloy does not cause age hardening at the time of soldering by heating with a burner and solder does not form a low m.p. brittle alloy with Au because solder does not diffuse.