Microstructural simulations and property evaluation of heat treated nickel free high nitrogen austenitic stainless steel

Abstract

Nickel Free High Nitrogen Stainless Steels (NFHNSS) are a group of newlinehigh-strength and non-magnetic austenitic steels used in medical and newlinepetro-chemical industries. These steels exhibit high strength, toughness along newlinewith high resistance to corrosion. Though Ni addition enhances many desirable newlineproperties in stainless steels, it causes allergy in human and animal bodies. newlineTo counteract these effects, low nickel and nickel-free austenitic stainless steels newlinewere developed. Manganese and nitrogen are commonly used as substitutes for newlinenickel in austenitic stainless steels. Addition of these elements promotes the newlineformation of nitrides as well as intermetallic precipitates during various heat newlinetreatments. Size and morphology of these precipitates strongly influence the newlinemechanical properties and corrosion behavior of NFHNSS. Thermodynamic, newlinekinetic simulations and microstructural simulations are important approaches to newlinedesign of alloys along with its precipitates and metallurgical process parameters newlineto obtain better material properties. Phase Field Modelling (PFM) is a new newlineapproach to simulate microstructure evolution in various materials. Even though newlinea lot of work on bio compactable behavior of NFHNSS have been carried out, newlineresearch of CALPHAD aspects of precipitate formations, influence of aging and newlineprecipitate phases on mechanical properties and corrosion behavior of NFHNSS newlineare very limited. Microstructural simulation of nitride precipitation by PFM for newlineNFHNSS has not yet been reported. newlineThis research focusses on the microstructural evolution in NFHNSS by newlinePFM, particularly chromium nitride (Cr2N) precipitation as well as precipitation newlinekinetics under different aging conditions using the CALPHAD approach through newlineThermoCalc and TC-PRISMA software. Results of the simulation studies were newlineexperimentally validated. Effect of precipitate morphologies on the tensile newlineproperties, stain hardening behaviour, hardness, toughness and corrosion behaviour newlineof NFHNSS under different aging temperatures has also been inve