304L/SA516Gr70不锈钢复合板焊接接头的组织与性能分析

Microstructure and mechanical properties of the welded joint of 304L/SA516Gr70 stainless steel composite plate

针对304L/SA516Gr70不锈钢复合板,采用钨极氩弧焊方法并选用ER309L焊丝焊接覆层和过渡层,选用E5015焊条电弧焊焊接基层。对焊接接头进行拉伸强度等力学性能测试,结果表明,拉伸试样断裂于母材,焊接接头的抗拉强度达573.4 MPa,断口呈明显的韧性断裂;观察接头金相组织表明,过渡层焊缝组织为黑色的蠕虫状和板条状铁素体存在于灰色的奥氏体基体上,此外基层母材与过渡层焊缝交界处存在一层脱碳层和厚度为40～50μm的凝固过渡层,这是由于碳元素在焊接过程中发生迁移的结果;X射线衍射分析显示,在接头焊缝金属中未发现有害相析出,保证了良好的接头性能。

The welding technology of 304L/SAS16Gr70 stainless steel composite plate is investigated.The transition region and clad metal are welded with ER309L welding wire by tungsten inert gas arc welding （GTAW）,and the base metal is welded with E5015 electrode by shielded metal arc welding （SMAW）.The mechanical properties of welded joints are tested.Results show that the tensile strengh of the joints reaches 573.4 MPa,and the joint failed in the position of base metal and it presents obvious characteristic of ductile fracture. Metallograph observation of welded joint illustrates that the microstructure of austenite and vermicular ferrite is formed in weld metal,and there are a decarburized layer and a solidification transition region with about 40-50 u m at interface between base metal and weld metal,it results in the migration of carbon element during welding.The XRD analysis indicates that no deleterious precipitation phases can be found in the weld metal.Consequently ,the welded joints with good quality are obtained.