INFLUENCE OF CEMENTITE PARTICLE-SIZE DIST RIBUTION ON MACHINABILITY AND TOOL LIFE OF HIGH-CARBON CR-BEARING STEELS

A study has been made on the relation between the distribution of ceme ntite (Fe3C) and the wear of tool in high carbon chromium bearing stee ls. Two kinds of materials with different state of cementite were prep ared by utilizing the thermo-calc program. The particle size and conte nt of cementite in these materials were controlled by heat-treatment. In the first stage, machinability was estimated, by using the material s of three kinds with a different particle diameter of cementite. In t he second of the experiment, the influence of interparticle distance o f cementite on the tool life was evaluated using the cutting tool of T iC: and SIG. The amounts oi tool wear were increased with increasing p article size and the areal ratio of cemented carbide. The amounts of t ool wear were also increased as the interparticle distance became shor t. The tool life of TiC tool was longer than that of SIC tool in cutti ng the same chemical composition of materials. Surface roughness (Rmax ) of the material was influenced by the particle diameter and interpar ticle distance of cementite. An experimental equation was proposed to estimated the tool life from interparticle distance of the precipitate d particle.