Effect of deep cryogenic processing cycles on surface roughness, dimensional stability and microstructure of high carbon high chromium tool steel for cutting tool and dies applications

Abstract

Abstract The main objective of this investigation is to analyze the influence of DCT cycles on microstructural evolution, surface roughness, hardness and dimensional stability of AISI D2 tool steel for cutting tools and dies applications. The cryogenic quenching was done using gaseous nitrogen. The AISI D2 tool steel was subjected to two DCT cycle: DCT-I (Hardening + DCT + tempering) and DCT-II (Hardening + tempering + DCT). The dimensional stability of AISI D2 tool steel was evaluated using standard Navy C-ring test. The coordinate measuring machine (CMM) was employed for the precise measurement of Navy C-ring subjected to different DCT cycle. The surface roughness was evaluated with R a (arithmetic mean roughness) and R t (total height of roughness profile) values using surface roughness tester. The microstructural features were analyzed using optical (OM) and scanning electron microscopy (SEM). The electrical resistivity and hardness of treated samples were measured using micro-Ohm meter and Vickers microhardness tester. Results showed that AISI D2 tool steel treated with DCT-I cycle exhibited greater surface finish, hardness and dimensional stability compared to DCT-II cycle. It is mainly attributed to the greater precipitation of finer carbides and balancing of tensile-compressive residual stresses.