Effect of tempering temperature and subzero treatment on microstructures, retained austenite, and hardness of AISI D2 tool steel

Abstract The presence of retained austenite in the hardening process tool steel often causes lower hardness compared to requirements and poor dimensional stability steel. purpose present research is determine relationships between tempering with without cryogenic treatment amount as-hardened D2 austenitizing temperature was 1020 °C, temperatures have variations 180 280 380 480 580 subzero has a −172 followed by at °C. This study aims appropriate obtain minimum percentage prevent mitigate failure AISI industrial application process. An optical microscope image processing software (Image-J analysis), as well Brinell Vickers testing, characterization method used this work. In general, plate martensite, bainite, austenite, primary secondary carbides are phases contained microstructure. Tempering effect increasing carbide precipitation decreasing content ( γ r 3,671%–2,769%). However, can provide more efficient martensitic phase transformation minimal 2,257%–1,199%). increase decrease °C–380 On other hand, phenomena cause an as-tempered sample before reexperiences significant °C due diffusion that decreases carbon content.