不锈钢TIG熔钎焊接头微观组织及力学性能
Microstructure and mechanical properties of TIG brazing of stainless steel
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摘要: 采用高温铜基S211和S201焊丝对不锈钢进行了TIG熔钎焊试验,运用OM,SEM,EDS分析了接头微观组织,通过拉伸试验评定了接头力学性能。结果表明,不锈钢接头具有熔焊与钎焊的双重性质,不锈钢上部靠近电弧区熔化,存在一个α+ε相熔合区;下部不锈钢未熔,为钎焊结合;焊缝基体为Fe在Cu中的过饱和固溶体相,基体上存在大量尺寸不等的α+ε相高温颗粒,焊缝区上部含高温颗粒多,下部含量少。两种接头均断裂于焊缝区,S211焊丝接头强度要高于S201焊丝,分别达到498.33 MPa和476.67 MPa,而S201焊丝接头的断后伸长率要高于S211焊丝,分别为19.6%和13.8%。Abstract: TIG brazing of stainless steel was carried out with S211 and S201 copper matrix filler metal.The microstructure and mechanical properties of the joint were studied by OM, SEM, EDS, Instron-testing machine, etc.The results show that the joint has a dual characteristic:the up side of the joint and a brazing part in the bottom part.A fusion zone consisting of αand εphases appears in the upper part and a brazing layer appears in the bottom part, which are joint to the stainless steel soundly.The microstructures of brazed seam are macro-homogeneous supersaturated solid solution of iron in copper matrix and high temperature granules consisting of αand ε distributed unevenly in the brazed seam, which consolidate the tensile strength of the brazed seam.The high temperature granules are distributed more unevenly in upper part than that of in the bottom and the sizes of them are different.Fracture occurs in the brazed seam of the two kinds of joints, S211 joint and S201 joint, in the tensile test.The S211 joint has higher tensile strength than S201 joint, compared 498.33 MPa to 476.67 MPa, whereas the S201 joint has higher extensibility, compared 19.6% to 13.8%.