Effect of bending parameters on formability of large curvature no-mandrel bending of 304 stainless steel tube
Aiming at the forming problem of multi-defect coupling in tube no-mandrel bending,the large curvature no-mandrel bending tests of 304 stainless steel tube were carried out under different bending parameters with the variation rate of tube wall thickness and the variation rate of cross-section short axis as the forming indexes.Combined with hardness test and microstructure characterization,the effect laws of bending parameters on bending forming and microstructure evolution were studied.The results show that with the increase of ben-ding speed,bending angle and relative tube diameter,the wall thickness variation rate shows an increasing trend,and the wall thickness thickening rate is always greater than the wall thickness thinning rate.At the same time,the cross-section distortion degree of the bent tube is increased.Under each bending parameter,the austenite to martensite transformation occurs in the inner and outer sides during tube bending.The martensite content and hardness are positively correlated with the wall thickness variation rate,and there is almost no martensite in the neutral layer.By selecting the appropriate process,a qualified bent tube with relative bending radius of 1.4 is finally bent.
NETL
NSTL
万方数据
