Influence of necking length on viscous medium outer pressure necking forming

Viscous medium outer pressure necking uses semisolid,flowable,highly viscous and certain rate sensitivity super-polymer as pressure carrying medium which can solve wrinkling problem during necking forming effectively and increase necking limit of specimen.Experiment and finite element methods were adopted to analyze the problems of the influence of different necking length on the process in viscous medium outer pressure necking.The necking limit and distribution rule of stress and strain of 1Cr18Ni9Ti thin-wall tube under the conditions of different necking length were obtained.Results show that the influence of necking length on viscous medium outer pressure necking forming is biggish.The ability of specimen to resist buckling is high and necking limit is big with the short necking length.