ＷＣ‐Ｃｏ超硬合金のクリープ破壊強度に及ぼすＷＣ粒度および結合相粒度の影響

Abstract

Bending creep-rupture strength of WC-(6-20)%Co high carbon alloys was investigated at 700-900°C for the rupture time up to 2 hr in relation to the carbide grain size (1.3-3.8 μm) and domain size of binder phase (60-500 gm).The results obtained were as follows; (1) As the test temperature increased, the creep-rupture strength of each alloy having a given domain size tended to show a maximum with increasing carbide grain size. On the other hand, the strength of the alloys having a given carbide grain size increased with increasing domain size. (2) In each alloy, it was generally observed that microcracks were first formed at WC/WC interfaces and then connected each other to yield a main stable crack. The growth rate of main stable crack, therefore, appeared to correlate with the formation rate of microcracks. (3) The high temperature creeprupture strength of WC-Co cemented carbides would be controlled by the WC/WC interfaces.