Improvement of surface conditions of 36 Cr Ni Mo 6 steel by ball burnishing process

Ball burnishing, a mechanical surface treatment, is becoming more popular as a finishing process. As results ball burnishing is noticed as a very simple way of surface mirror finishing and surface work-hardening. Applying the optimal input parameters, a pre-machined surface roughness Ra about of 3.01 mu m can be finished to approximately 0.30 mu m, whereas an initial hardness HRA about 66.35 can be increased to 71.33. A metallographic observation and some measurement of micro-hardness show that the depth of penetration strengthened by plastic surface deformation (PSD) reaches 100 mu m. Results analysis show that burnishing force, burnishing ball radius and number of ball burnishing tool passes have the most significant effects on both surface responses (Ra and HRA). For the generating of high surface qualities and strengthening superficial layers, an alternative to chip-forming process and heat treatments can be given by ball PSD process.