Cutting performance and wear mechanism of spark plasma–sintered silicon nitride ceramics tool in dry turning of 41Cr4 hardened steel

Cutting performance and wear mechanism of spark plasma-sintered Si3N4 (SN91) and Si3N4/WC (SW10) ceramic tools in the dry turning of 41Cr4 hardened steel are studied. SN91 tool shows better wear resistance than SW10 tool and commercial ceramic tool SW500 and cemented carbide tool YG8 under the same cutting conditions. The better cutting performance of SN91 can be attributed to its excellent high-temperature flexural strength. The most significant factor affecting the tool life of SN91 is the cutting speed. A higher material removal volume can be achieved at a low cutting speed, large depth of cut, and large feed rate. A long cutting distance/time can be achieved at a low cutting speed, small depth of cut, and feed rate. At a cutting speed of 103.62 m/min (ap = 0.1 mm, and f = 0.05 mm/rev), the wear mechanisms of SN91 are adhesion, oxidation, and diffusion, and no crater wear is observed on the rake face. At a cutting speed of 214.31 (ap = 0.3 mm and f = 0.05 mm/rev) and 314 m/min (ap = 0.2 mm and f = 0.05 mm/rev), the failure forms of SN91 tool are mainly rake face crater wear and flank wear; the wear mechanisms of rake face are diffusion, abrasion, and oxidation; and the wear mechanisms of flank face are abrasion, adhesion, and oxidation. The failure forms of SW10 tool are mainly rake face crater wear and flank wear, and the wear mechanisms are diffusion, abrasion, adhesion, and oxidation.