Material properties and residual stresses of welded high strength steel and hybrid I-sections

High strength steel (HSS) I-sections are gaining increasing popularity compared with conventional strength steel counterparts, mainly due to its higher strength-to-weight ratio. Meanwhile, there has been growing interest in hybrid I-sections, which are made of different strength steels for flange and web plates, because of the increased need of maximising material utilization. This study investigates the welding effect on the material properties and residual stresses of welded HSS and hybrid I-sections. Tensile tests of coupons machined from both virgin plates and within the welded I-sections were carried out, followed by a metallographic analysis of welding position. It was found that the welding effect on the mechanical behaviour of steel materials varies, depending on the chemical composition and microstructure. Residual stress measurements for HSS and hybrid I-sections covering four web slenderness were conducted. The measurement results demonstrate that the effect of steel strength grade of constitutive plates on residual stress distribution of I-sections is negligible, and a new residual stress distribution model is proposed for welded HSS and hybrid I-sections examined in this study.