摘要
Abstract
To improve the welding efficiency and quality of Q390 low-alloy high-strength structural steel,a multi-layer and multi pass double wire welding process is proposed for Q390 thick plates,which includes four stages:bottom welding,fill welding 1,fill welding 2,and cover welding.The results show that multi-layer and multi pass double wire welding does not change the chemical composition of the base material,but promotes the transformation of the steel plate structure from columnar coarse crystals to strip-shaped fine crystals,significantly improving the hardness of the weld seam,and the hardness of the base welding is greater than that of the filler welding and the hardness of the cover welding;The mechanical properties of Q390 thick steel plate welded joints are excellent,with an average tensile strength of 531.7MPa,an average yield strength of 338MPa,and an average elongation rate of 21.2％.The welding residual stress in the weld area is relatively high,with maximum residual stresses perpendicular and parallel to the weld direction reaching 377MPa and 351MPa,respectively.Although both do not exceed the yield strength of Q390 base metal,it is still recommended to adopt appropriate treatment methods for thick plate double wire welds to reduce post weld residual stress.关键词
Q390低合金高强结构钢/双丝焊接工艺/接头力学性能/焊接残余应力Key words
Q390 low-alloy high-strength structural steel/double wire welding process/mechanical properties of joints/welding residual stress
