Influence of sequential pre-processing on the structural and tribo-mechanical properties of Vancron 40 tool steel

Tribo-mechanical properties of Vancron 40 tool steel subjected to selected-multistage sequential surface treatments were investigated with the aim to optimize its wear resistance. The surface modifications included: heat treatment, mechanical processing (grinding/turning/slide burnishing) and gas nitriding. The lowest of both sample wear and dynamic friction were obtained for the materials subjected to sequential turning-burnishing-nitriding (TBN) processes. Microstructural observations confirmed that the subsurface plastic deformation (SSPD) within the nitrided layer was the main contributor to wear resistance. The specific wear rate for three-stage processed substrates was 4.1 mm 3 /Nm, a 15 % decrease, whereas the specific wear rate of the ball was 0.38 mm 3 /Nm, i.e. a three-fold increase as compared with conventional grinding-nitriding (GN). The dynamic friction was 0.57, hence 22 % lower than before. The improved tribo-mechanical properties reflect the synergy effect of mechanical processing procedures applied prior to nitriding. • Surface/sub-surface microstructure of Vancron 40 steel is greatly influenced by sequential pre-processing. • The sequential processing of Turning-Burnishing-Nitriding demonstrates the best wear resistance. • Controlled plastic deformation enables Turning-Burnishing to be a feasible industrial alternative to Grinding.