| Austenitic stainless steel has been used in various industries widely due to its excellent corrosion resistance and non-magnetic.With rich nitrogen,the strength and the corrosion resistance can be improved for high nitrogen austenitic stainless steel,but the recovery is retardated.Inappropriate hot working process will lead to strain concentration in the process of hot rolled steel,so the formability of the product is affected seriously.Therefore research on the hot deformation behavior of high nitrogen austenitic stainless steel is necessary.And the theoretical guidance for the hot rolling process of high nitrogen austenitic stainless steel will be provided.The hot deformation behavior of Cr17Mn17Mo3 NiN austenitic stainless steel(H1)was investigated by Gleeble-3500 in the temperatures range of 950-1100 ? and strain rates range of 0.01-1 s-1.The influence of different deformation parameters on the flow stress curve was analyzed.The evolution of microstructure was revealed by means of metallographic microscope(OM)and transmission electron microscopy(TEM).The hot deformation constitutive equation was constructed based on the hyperbolic sine function.The hot processing map was established on the basis of the dynamic material model(DMM),and the optimized hot deformation processing window of Cr17Mn17Mo3 NiN austenitic stainless steel was identified.The scientific reference for the promotion and application of this stainless steel was achieved.The main conclusions were drawn as follows:The flow stress decreases with the increase of the temperature at the same strain rate;however,the flow stress decreases with decrease of the strain rate at the same temperature.Under the condition of high temperature and low strain rate,the dynamic recrystallization of Cr17Mn17Mo3 NiN austenitic stainless steel was the main softening mechanism and the degree and the grain size of dynamic recrystallization were increased.However,the dynamic recovery of stainless steel was the main softening mechanism at high temperature and high strain rate.The main nucleation mechanism of Cr17Mn17Mo3 NiN austenitic stainless steel was the grain boundaries of the original austenite grains protruded,and the rotation mechanism of the subgrains near the grain boundary played a complementary role in the nucleation of recrystallization.The activation energy of hot deformation for Cr17Mn17Mo3 NiN austenitic stainless steel was 551.36 kJ/mol.When the strain rate is 0.01-0.1 s-1,the optimized hot deformation processing window of the Cr17Mn17Mo3 NiN austenitic stainless steel was identified as 1000-1050 ?. |
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