Research On The Stamping Forming Of 304L Dished Head

Along with the national energy strategy is inclining to the new energy,liquid hydrogen,liquid nitrogen and liquid natural gas as the representative of the new energy industry have had a rapid development in recent years,the demand of austenitic stainless steel pressure vessel as an important storage and transportation equipment of low temperature liquid has increased,especially the demand of its head as an important part of a pressure vessel has increased more rapidly.Using dished head can significantly improve the volume of the container when the pressure vessel is at the same length,while 304 L dished head has always been the problem in the production of pressure vessel.However,high martensite content,large springback amount,the wrinkle and bulge are always serious problem in current stamping production of 304 L dished head.The deformation of 304 L induced martensite transformation is mainly related to Ms,Md and nickel equivalent,while the chemical composition is an important factor to Ms,Md,and nickel equivalent.In this paper,the chemical composition of 304 L was obtained by chemical composition analysis of 304 L,then the Ms and Md could be calculated.The relationship between martensite transformation and plastic deformation was obtained by the calibration test of 304 L martensitic transformation.FEM software MSC.Marc had been used to simulate the stamping process of dished head,the results showed that the relationship between plastic deformation and the stamping depth,so the sheet metal first need to cold stamp270 mm,then heat the flange part to 160 for the ?next stamp.The influence of the maximum BHF,the gap between punch and die,the spingback of dished head diameter,the minimun wall thickness and stamping forming load were simulated by the FEM software MSC.Marc,the results showed that the quality of dished head was good when the maximum BHF was 22000 kN,the gap between punch and die was 11 mm.And the influence of the parameters of drawbead on the spingback of the dished head diameter was studied through the orthogonal experiment,the results showed that the height of the drawbead had a significant influence,obtained the best parameters of the drawbead was the height of the drawbead was 20 mm,the outside fillet R1 of the drawbead was 20 mm,the inside fillet R2 of the drawbead was 20 mm,the outside fillet r1 of the groove was 30 mm.According to the optimized parameters of drawbead,the gap between punch and die,the mold was designed.The experiments had been executed based on the optimized process parameters,the minimun wall thickness was 9.3mm,the maximum wall thickness was 10.3mm,the amount of martensitic transformation was 8.6%,the spingback of the dished head diameter was 3mm,shape of the head was good,the maximum springback of arc was 1.2mm,the dished head was qualified,no defects such as bulge and wrinkle was found.