焊接工艺参数对Q690D高强钢多层多道焊缝缺欠的影响

Effect of Process Parameters on Welding Imperfection of Multi-pass Welding for Q690D High Strength Steel

针对液压支架结构件用Q690D高强钢多层多道焊焊缝,通过焊缝横截面形貌分析、X射线检测等分析手段研究了焊接电流、保护气体流量、焊丝干伸长、坡口拼装间隙等焊接工艺参数对焊缝缺欠类型、位置与数量的影响,并通过拉伸试验、冲击试验测试了焊接接头性能。结果表明,液压支架结构件用Q690D高强钢多层多道焊焊缝中缺欠以气孔、未熔透和未熔合为主,其中气孔约占43%,未熔透约占30%,未熔合约占23%;缺欠主要集中于焊道根部、焊缝内、焊道与母材熔合线处、焊道之间等位置,其中,焊道根部缺欠数量约占54%,为焊缝缺欠最集中的位置;试验范围内,焊接电流、保护气流量、焊丝干伸长等参数对焊缝内部缺欠影响较大,而对焊缝根部缺欠无明显影响;拼接间隙对焊缝根部未熔透、气孔等缺欠有明显的影响作用,当拼接间隙为2mm时,可有效减少根部缺欠;保护气种类主要影响焊缝成形质量,而对焊缝缺欠无明显影响;优化工艺参数后,焊缝缺欠明显降低,无明显未熔透、未熔合等缺欠,气孔率约2.1%,接头抗拉强度达798.6MPa,接头性能良好。

Aiming at the multi-layer and multi-pass welding seam of Q690D high strength steel for fully mechanized hydrau‐lic support structural parts,the effects of welding process parameters such as welding current,shielding gas flow,wire exten‐sion and assembly gap on the type,position and quantity of weld defects were studied by section analysis and X-ray detec‐tion.The joint performance was tested by tensile test and impact test.The results showed that the weld bead were mainly pores,incomplete penetration and incomplete fusion,among which pores account for about 43%,incomplete penetration ac‐counts for about 30%,and incomplete fusion accounts for about 23%.The defects were mainly concentrated in the root of the weld,the inside of the weld,the fusion line between the weld and the base metal,and between the welds.Among them,the number of weld root defects accounts for about 54%,which was the most concentrated position of weld defects.In the test,welding current,shielding gas flow rate,wire extension and other parameters had a great influence on the internal de‐fects of the weld,but had no obvious influence on the root defects of the weld.The splicing gap had a significant effect on the defects such as incomplete penetration and porosity at the root of the weld.When splicing gap was 2 mm,the root defect could be effectively reduced.The type of shielding gas mainly affected the quality of weld formation,but had no obvious ef‐fect on weld defects.After optimizing the process parameters,the weld defects were obviously reduced,and there were no obvious defects such as incomplete penetration and incomplete fusion.The porosity was about 2.1%,the tensile strength of the joint was 798.6 MPa,and the joint performance was good.