Deep cryogenic treatment (DCT) is one of the most recent processes being used to treat tool steels. It is a supplementary treatment where components are treated below subzero temperatures for several cryo-soaking hours. This paper focuses on to study the effect of deep cryogenic treatment on Thermo mechanical properties of AISI H-13 tool steel. Deep cryogenic treatment at 32 hours of cryo-soaking time is applied and thermo mechanical performance of tool steel was analyzed by using pin on disk high temperature wear testing and stress rupture testings. The microstructural evolutions during DCT were evaluated by using scanning electron microscope (SEM). It was observed that microstructural modifications like increase in carbide density, fine and uniform martensitic structure during DCT had significantly improved properties.

Duplex stainless steels have dual phase microstructure consisting of approximately equal volume fraction of ferrite and austenite. Volume fraction of phases significantly affects mechanical properties of duplex stainless steels. In the present work, effect of solution treatment temperatures (in the range of 900-1150 °C) on microstructure (phase % of ferrite and austenite) and mechanical properties like tensile (room temperature (RT)) and Charpy impact (RT and-25 °C) of duplex stainless steel, 2205 were investigated. Analysis indicates that with increase in solution treatment temperature, % ferrite phase increases and % austenite phase decreases. 50-50% combination of both phases was obtained around 1020 °C. Tensile test results indicate that yield strength and ultimate tensile strength remains similar for all temperatures. Maximum Charpy strength was obtained at 1050 °C. A sudden drop in charpy strength was observed at 950 °C for both RT and-25 °C tests. Microstructural and SEM analysis reveals the presence of intermetallic phases like sigma (σ) and chi (χ), precipitated at ferrite/ferrite boundary and ferrite/austenite grain boundary which may cause the decrease in impact properties. Index Terms-Duplex stainless steel, chi (χ) and sigma (σ) phase.