Cross-sectional deformation of high strength steel rectangular welded tube in rotary draw bending with different constitutive relationships

Abstract

An accurate constitutive relationship of rectangular welded tube is important to improve prediction accuracy of cross-section deformation in rotary draw bending by simulation. So five constitutive relationships of QSTE700 high strength steel rectangular welded tube were selected and determined. And five FE models of rotary draw bending process of rectangular welded tube by using these five constitutive relationships were built. Based on the above FE models, the effect of different constitutive relationships of rectangular welded tube on cross-sectional deformation in rotary draw bending process was studied. The results showed that height deformation ratio and width deformation ratio obtained by simulations were gradually increased to approach experimental results when using mixture-model, homogeneity model, W1H model, W2H model and W4H model, successively, and the simulation results obtained by W4H model were closest to experimental results, so the “weld and four heat affected subzones” model was suitable for describing the constitutive relationship of rectangular welded tube, which further meant that when the heat-affected zone was subdivided into more subzones, the constitutive relationship of QSTE700 rectangular welded tube became more accurate.