Microstructure and Properties of Electron Beam Welded Tantalum-to-Stainless Steel Joints

摘要:

研究了钽与不锈钢电子束焊接接头组织、缺陷特征及力学性能。电子束热源作用位置影响到接头成形，偏不锈钢0.2 mm进行焊接接头成形较好。焊缝为细小枝晶组织，Fe元素含量较高，形成的ε相（Fe2Ta）和μ相(FeTa或Fe7Ta6)为弥散分布。在钽侧熔合线处ε相和μ相为层状分布，在焊接应力作用下易形成微裂纹缺陷。接头焊缝区普遍硬度较高，而钽侧熔合线处变形协调能力较差，存在裂纹源，导致接头拉伸时在该处断裂。接头抗拉强度不高，仅为255 MPa

Abstract:

The microstructure, defect characteristics, and mechanical properties of electron beam welded (EBW) tantalum-to-stainless steel joints were investigated. Joint formation was influenced by the position of the EBW heat source. with a well-formed joint was obtained when the heat source was deviated by 0.2 mm towards the stainless steel. The weld is composed of fine dendrites with high elemental Fe content and homogenously-dispersed ε (Fe2Ta) and μ (FeTa or Fe7Ta6) phases. However, ε and μ phases formed at the tantalum fusion line had lamellar distribution and micro-cracks are easily formed in this region under welding stress. Although the weld zone has high hardness, the poor deformation compatibility of the fusion line at the tantalum side and the existence of crack sources lead to fracturing during the tensile test. The tensile strength of the joints was found to be low, 255 MPa