PHASE-TRANSFORMATION AND RESIDUAL-STRESS ANALYSIS IN CRYO-TREATED SINGLE-POINT CUTTING-TOOL

A finite element method is carried out to compute temperature, phase t ransformation and residual stress distribution for a single point high speed steel tool. Thermophysical and mechanical properties are taken as a function of temperature. The residual stresses formed due to quen ching are calculated using thermo-elastic-plastic approach. The cryo-t reatment of a high speed steel tool at 173K gives about 16% higher mar tensite as compared to oil quenching. The residual stresses induced in the case of cryo-treatment are higher as compared to oil quenching at 300K. Experiments were done to determine Rockwell hardness number and microstructure of the HSS T1 type tool before and after the cryo-trea tment. The results, show improvement in hardness and increase in marte nsite transformation.