Effects of thermal oxidation and vibratory treatments upon the strength characteristics of low-cobalt WC-Co hard alloys

Conclusions

• 1. Thermal-oxidation treatment and diamond grinding applied to low-cobalt (4–6% Co) tungsten hard alloys remove their defective surface layers, thereby increasing their transverse-rupture strength and impact strength by 20–30%. Because of the higher productivity achieved in it and its lower cost, however, the thermal-oxidation process must be regarded as superior to diamond grinding.

• 2. Use of subsequent vibratory treatment brings about a further improvement in the mechanical characteristics of alloys of this type (amounting to 40–80% compared with untreated specimens), which is a consequence of vibratory hardening by hard-alloy balls.

• 3. In cases where a large allowance is to be removed from a hard-alloy component, it is advantageous first to subject the latter to thermal oxidation treatment and then bring it to the required dimensions by vibratory treatment.