Influence of Cutting Edge Geometry on Deformation Induced Hardening when Cryogenic Turning of Metastable Austenitic Stainless Steel AISI 347

In recent years deformation induced surface hardening was carried out to enhance the component performance of metastable austenitic steels. To be able to induce such a phase transformation from austenite to martensite in the workpiece surface layer, high mechanical loads and low process temperatures are required. Therefore, cryogenic CO2-snow cooling is an appropriate method to assure a low heat influence on the workpiece. High mechanical loads can be obtained by high feed. However, this causes relatively rough surfaces due to the process kinematics. In this context, the influence of cutting edge geometry on deformation induced surface hardening and resulting surface roughness is investigated. With a variation of the geometry of the cutting edge, especially the cutting edge radius, mechanical loads and thus the amount of martensite formed were adjustable.