Investigation on Surface Integrity of STAVAX ESR AISI 420 Martensitic Stainless Steel by Cryogenically Treated Steel Balls with Low Plastic Burnishing Tool

Abstract

Low plasticity burnishing (LPB) is a new method of surface improvement, which raises the burnishing to the next level of sophistication. LPB can provide deep compression for improved surface characteristics. The study focuses on the surface roughness, micro-hardness and surface integrity aspects on soft AISI 420 STAVAX ESR martensitic stainless steel AISI 420 material. This material is pronounced as difficult to cut materials like titanium, Inconel 718 etc. The investigation of surface integrity was done on this materials in terms of operating parameters like sliding speed, feed rate and depth of penetration (DOP) identifying the predominant factors among the selected parameters. The steel balls used were cryogenically treated at sub zero temperature of -176 degrees. Sub-surface micro-hardness study were also done to asses the depth of compression altered zone, surface roughness and surface hardness. The process can be applied to critical components effectively as the LPB process has cycle time advantages and also low investment cost. This can be also realized by introducing on high speed machines. This process was studied by using cryogenically treated different ball diameters at various operating parameters. This also improved on concentricity of work material. More the depth of compression produced low surface roughness at low sliding speed, feed rate with larger ball diameter. The DOP also helps to improve on surface and sub-surface hardness and close roundness. There are limitations on DOP beyond which the surface deteriorated.