Research On Microstructure And Property Of Cold Rolled 301 Stainless Steel After Reverse Transformation

Austenitic stainless steels were widely used as engineering structure material in industry and daily life, for its good formability and excellent corrosion resistance. But the strength and hardness austenitic stainless steels is low, the product failed due to the yield deformation, which affect the service life of the product. At present, the grain refining becomes the important way to improve the strength and hardness of austenitic stainless steel, and improve the product quality. Annealing after large deformation is an good method to abtain ultra-fine crystal structure, after that, the change of the mechanical properties and corrosion resistant will affect the use of austenitic stainless steel.In this paper, the 301 austenitic stainless steel annealing in the temperature between 650℃~850℃ for different holding time after 90% cold rolling deformation to abtain ultra-fine crystal structure. We studied the organization evolution 、 strengthening mechanism、 mechanical properties and corrosion resistance of the steel after reversion. The main work and conclusions of this paper are as follows:Austenite in 301 austenitic stainless steel change into martensite after 90% cold rolling, and the content of martensite is about 95.4%, The reversion transformation temperatue of the material is measured by DSC and Gleeble-3500.After reversion, the martensite reduce and austenite increase, the small grains form the fine crystal structure; at the same temperature, the content of martensite decrease and the austenite grain size increase when the holding time and cycle times increase.After reversion, the yield strength, tensile strength and hardness of stainless steel increases, the sample in 750℃ for 10 minutes has good comprehensive mechanical properties,micro-hardness is 362HV0.3,the yield strength is 744 MPa,the tensile strength is 890 MPa,the elongation is 37%,due to the grain refinement; at the same temperature, the yield strength, tensile strength and hardness of stainless steel reduce and the elongation increase when the holding time increase.The pitting potential of the cold rolled 301 stainless steel after reversion has been measured by cyclic voltammograms curve method. The pitting potential of sample in 750℃ for 10 minutes is 447 mV, which proved that the corrosion resistance of stainless steel is improved after reversion transformation.