Conventional 22K Au jewelry alloys are comparably soft in the as-cast and soft-annealed state (~60HV1). Hardening by alloying can be done without detrimental effects on color, melting, corrosion and working properties, however, it is still a challenging task. In contrast to previous studies, the present work focuses on hardening by alloying with conventional base metals. It is shown that cobalt additions increase as-cast hardness and provide the possibility for further significant hardness increase by age-hardening heat treatment (up to ~260HV1). The results of extended property testing, as well as field tests with industrial partners, are discussed. This research project has been funded by the World Gold Council under G.R.O.W. RP03-02.

Author: Dr. Jörg Fischer-Bühner