High-speed intermittent turning of GH2132 alloy with Si3N4/(W, Ti)C/Co graded ceramic tool

Abstract

In this paper, a new Si3N4-based graded ceramic tool was prepared by hot press technology The tool was toughened by microscale (W, Ti)C, nanoscale Si3N4, and metal Co. The graded structure combing with proper composition distribution introduced thermal residual compressive stress into the surface layer of the tool according to the FEM analysis. The performance of the tool in high-speed intermittent turning GH2132 alloy (equivalent to A286) was studied in contrast to one homogeneous tool. The cutting forces analysis indicates that the inserts endure periodic mechanical shock in the intermittent cutting process and the mechanical shock is more serious when the tooth engages the workpiece than when it disengages the workpiece. The tool failure modes observation shows ladder-like fracture under thermal and mechanical shock in the intermittent cutting process. Tool failure mechanisms involve chipping, flaking, microcracks, and adhesion. The graded tool shows better thermal and mechanical shock resistance than the homogeneous tool due to the formation of residual compressive stress.