Study On Microstructures And Properties Of Austenitic Steels After High Pressure Heat Treatment

In this paper,301 stainless steel and TWIP(Fe-19Mn-0.6C)steel are taken as the research objects.Two kinds of steel are cold rolled 87.5% and high pressure heat treatment.The microstructural of the two austenitic steels was observed by optical metallography,scanning electron microscopy,X-ray diffraction and electron backscatter diffraction.The mechanical properties and corrosion resistance of the two austenitic steels were measured by micro Vickers hardness tester,universal tensile tester and electrochemical workstation.The results show that after high pressure heat treatment,the increase of annealing temperature and pressure is conducive to the reversal of martensite to austenite in 301 stainless steel.With the temperature increasing,301 stainless steel strength gradually reduced,plastic gradually increased;With the holding time increasing,the strength of 301 stainless steel first increased and then decreased,and the plasticity gradually increased.At the pressure of 5GPa,the temperature of 750 ℃ and the holding time of 60 min,the excellent properties of yield strength of 701 MPa,tensile strength of 1300 MPa,elongation of 65.1%,and strong plastic product of 84630MPa% can be obtained.At the same time,after the high-pressure heat treatment of the cold-rolled 301 stainless steel,with the holding time increasing,the corrosion resistance has been improved to a certain extent.After high pressure heat treatment,the increase of temperature and holding time is beneficial to recrystallization of TWIP steel.The higher temperature and the longer holding time,the less second phase precipitates;With the temperature increasing,the strength of TWIP steel decreases gradually,and the plasticity increases first and then decreases;with the holding time increasing,the strength of TWIP Steel decreases gradually,and the plasticity increases gradually;the excellent properties of yield strength of 374 MPa,tensile strength of 1069 MPa,elongation of 74%,and strong plastic product of 79106MPa% can be obtained at the pressure of 5GPa,the temperature of 750 ℃ and the holding time of 30 min.At the same time,the corrosion resistance of TWIP steel has been improved with the increase of temperature in a certain temperature range after high pressure heat treatment.When the annealing temperature is higher than 800 ℃,the corrosion resistance is better than original TWIP steel.