Study On Plastic Formability Of Metastable Austenitic Stainless Steels Cold-rolled Sheet

301L cold-rolled and reinforced sheet is the main materials on creating light vehicle body. With the growing demand for stainless steel passenger cars at home and abroad, the localized demand for 301L cold-rolled sheet is increasingly urgent. However, domestic sheets are prone to crack, local split, wrinkling and other phenomenon for plastic molding. In order to solve these problems in application, using domestic and Japanese sheet, the paper studies the performance and process of stamping by comparative test.The research content of this article can be divided into basic and applied two parts. In basic research, doing tensile test with 301L-MT (Chinese) and 301L-ST (Chinese) sheet at low strain rate, to get mechanical properties, strain hardening exponent, plastic strain ratio and other parameters which associated with stamping properties of materials. These parameters are the basis of studying sheet forming properties. In applied research, doing bending comparative test with 301L-DLT (Chinese) and SUS301L-DLT (Japanese) at room temperature, to study the influence of material properties and process parameters on bending parts. Doing Erichsen test with 301L-MT,301L-ST, 301L-DLT and SUS301L-DLT sheet at room temperature to analyze the relationship between the amount of martensite transformation and hardness of the molding parts. Along the direction of rolling and perpendicular to the rolling of 301L-MT and 301L-ST bulge-forming parts, doing forming limit test to measure the equivalent strain and the amount of martensite transformation, and then study the influence of strain-induced martensitic transformation on the performance of sheet bulging in the deformation.After experimental determination and analysis, the yield strength and of 301L-MT sheet were significantly greater than 301L-ST. The anisotropy of yield strength is not obvious. The anisotropy of tensile strength, yield ratio and break elongation is largely obvious. The n of 301L-ST is greater than 301L-MT, r and△r is slightly less than 301L-MT. The anisotropy of 301L-MT sheet is obvious than 301L-ST. 301L-MT produce ears in directions of 0°and 90°easily and more likely appear non-uniform deformation. In contrast, the forming properties of lower hardened grade 301L-ST is better. The IE and the amount of martensite transformation of Erichsen molded parts of 301L-ST are higher than 301L-MT. Whether rolling direction or perpendicular to rolling direction, the amount of martensite transformation of 301L-MT is significantly higher than 301L-ST. Along the rolling direction, the equivalent strain intensity is influenced largely by the material properties. Perpendicular to the rolling direction, loading forces have obvious impact on the equivalent strain intensity. Bending tests show that SUS301L-DLT brings strain-induced martensite transformation is easier than 301L-DLT. Thick sheet relatively has a high amount of martensite transformation. The bending deformation behaviors of domestic and import sheets are very close when the bending angle is less than or equal 90°. Erichsen formability properties of import sheet are superior to domestic sheet.