超硬合金工具材料の微視的変形挙動の有限要素法による解析

Abstract

The microscopic behavior in deformation of WC-Co alloys is analyzed for the two-dimensional models of the alloy by applying the finite element method. Using ten different models of the alloy which are assumed to consist of simplified microstructures exhibiting WC particles dispersed in Co matrix, the effects of the area fraction of WC phase, the shape of WC particles and the bridge formation between adjacent WC particles, on the distributions of micro-stress and micro-strain and the initial macroscopic yield stress of the alloy are determined. The analytical results show that the initial macroscopic yield stress increases with an increase in the area fraction of WC phase, and it tends to decrease as the direction of the WC/Co interface is closer to the direction of maximum shear stress. For the alloy having circular particles with large variation of the thickness of Co phase, the initial macroscopic yield stress is smaller than that for the rectangular shape with constant thickness of Co phase. It is also found that the initial macroscopic yield stress with the bridge formation between adjacent WC particles is larger than that without the bridge formation in overall range of macroscopic stress state except for a particular stress state.