Effect Of Several Typical Alloying Elements On Microstructure And Properties Of 301L Stainless Steel Used In Rail Vehicles And Physical Mechanism

The stainless steel rail vehicle body material is often made of 301L stainless steel,and different strength grades can be applied to different parts of the rail vehicle body.As a metastable austenitic stainless steel,301L stainless steel will undergo deformation-induced martensitic transformation during cold deformation.Alloying elements play a decisive role in the difficulty and transformation of martensite transformation.Thus directly affecting the microstructure and mechanical properties of the rolled samples.In this paper,301L stainless steel with different Ni,N and Mn contents was prepared by aluminothermic reaction method.The effects of three alloying elements on the as-cast and as-rolled microstructure of 301L stainless steel were studied by optical microscopy?OM?and scanning electron microscopy?SEM?.The effect of three alloying elements on mechanical properties of HT-301L and N-301L stainless steels by room temperature tensile test and microhardness test.1.The as-cast 301L stainless steel contains two phases of ferrite and austenite.After annealing at 1200°C,the phase transition from ferrite to austenite occurs,and the amount of ferrite decreases,almost disappearing.Almost disappeared.The austenite in the sample after rolling undergoes a phase transformation to form stress-induced?'-martensite.With the increase of Ni content,the volume fraction of?'-martensite in the as-cast samples decreased gradually,and the tensile strength increased first and then decreased,while the yield strength decreased significantly.The elongation increases with the increase of Ni content,and the microhardness increases first and then decreases with the increase of Ni content.As the Ni content increases,the yield strength and tensile strength of the first cold rolled annealing sample decrease remarkably,while the elongation increases remarkably.2.The content of N element has a very significant effect on the morphology of ferrite in as-cast 301L stainless steel.With the increase of N content,ferrite changes from long strip to short rod and island.When N content reaches 0.13%,the ferrite is mainly needle-like and island-like.With the increase of N content,the?'-martensite in the rolled HT-301L stainless steel gradually decreased,and the morphology did not change much.With the increase of N content,the yield strength,tensile strength and microhardness of HT-301L stainless steel increased significantly,but the elongation increased first and then decreased.With the increase of N content,the yield strength and tensile strength of the annealed N-301L stainless steel increased slightly,while the elongation decreased significantly.3.With the increase of Mn content,the?'-martens content in the rolled HT-301L stainless steel gradually decreased,and the lath martensite gradually broke.When the Mn content increased to 1.42%,the martensite content decreased to about10%.As the Mn content increases from 1.00%to 1.42%,the yield strength of the rolled HT-301L stainless steel decreases first and then increases,and the tensile strength,elongation and microhardness increase gradually.With the increase of Mn content,the yield strength of the annealed state N-301L stainless steel decreases first and then increases,the tensile strength decreases gradually,the elongation increases gradually,and the elongation reaches up to 31.10%.4.The 301L has good strength and plasticity when the stacking fault energy is 15mJ·m^-218 mJ·m^-2or M_d3030 is 35³7?,while other parameters,especially Ms,have less influence.