20G/316L双金属复合管弧焊接头组织与性能

Microstructure and mechanical properties of TIG welded 20G/316L clad pipe joint

关键词:  G/316L复合管  TIG焊  显微组织  力学性能

Key words:  G/316L clad pipe  TIG  microstructure  mechanical properties

摘要:

对20G内衬316L复合管进行了TIG焊对接试验,并对接头进行了拉伸、弯曲、冲击、压力测试以及无损探伤,利用光学、扫描电子显微镜以及化学分析方法对接头组织和主要合金元素的扩散进行了分析.结果表明,焊缝分为碳钢层、碳钢与过渡层间的扩散层、过渡层和不锈钢层四个区域.扩散层焊缝组织为马氏体+残余奥氏体,过渡层为奥氏体组织,而不锈钢层则为胞状树枝晶.在试验参数下,接头各项力学性能优良,接头无缺陷.焊缝根部Ni,Cr合金元素与焊接材料相比无明显变化,采用过渡焊丝起到了保持根部焊缝合金元素含量的作用。

Abstract:

Tensile strength, bending strength, impact toughness and non-destructive inspection tests of TIG welded 20G/316L clad pipe joint were carried out.The microstructure and the diffusion of the major alloying elements were analysed using optical microscopy, SEM and chemical analysis.The results showed that the weld can be divided into four layers including carbon steel layer, diffusion layer, transition layer and stainless steel layer.The microstructure in diffusion layer was characterized by the martensite and retained austenite.The transition layer only contained austenite, and the stainless steel layer included afterbirth-like crystal.The defect-free joint was produced and performed well under the experimental parameters.The concentration of nickel and chromium element in weld root did not decrease compared with the corresponding welding materials, which proved that the employment of transition welding wire could maintain the concentration of the major alloying elements in welding root.