钨极氩弧焊焊接粉末冶金高铬铸铁/低碳钢的焊接性能及组织演变  

Weldability and microstructure evolution of powder metallurgy high chromium cast iron/low carbon steel welded by gas tungsten arc welding

作　　者：钟斯远 肖平安[1] 赵吉康 ZHONG Siyuan;XIAO Ping'an;ZHAO Jikang(College of Materials Science and Engineering,Hunan University,Changsha 410082,China)

机构地区：[1]湖南大学材料科学与工程学院,长沙410082

出　　处：《粉末冶金技术》2024年第4期346-353,共8页Powder Metallurgy Technology

基　　金：国家自然科学基金资助项目(20151075506,51574119)。

摘　　要：以粉末冶金高铬铸铁和低碳钢为原材料,采用多道次手工钨极氩弧焊,研究了焊接电流对焊缝组织演变和力学性能的影响,提出了焊接接头组织演化模型,并探讨了其断裂机理。结果表明,焊接接头的抗拉强度在焊接电流为140 A时达到538.1MPa,分别是烧结高铬铸铁和低碳钢抗拉强度的95.3%和97.4%。由于二次回火和合金元素扩散/偏析的作用,焊接接头的显微硬度在水平方向上由高铬铸铁一侧向低碳钢一侧逐渐降低,而在垂直方向则呈M形分布。当焊接电流为140 A时,焊缝的熔合区主要由奥氏体和回火马氏体组成,在熔合区与低碳钢母材之间存在一个单一奥氏体柱状晶区;在熔合区与烧结高铬铸铁母材之间,存在一个柱状高铬铸铁区域,该区域的碳化物为粗糙树枝状,沿基体晶界分布。Powder metallurgy high chromium cast iron(PM HCCI)and low carbon steels(LCS)were welded by multi-pass manual gas tungsten arc welding(GTAW).The effects of welding current on the microstructure evolution and mechanical properties of the weld joints were systematically investigated,the microstructure evolution model of the weld joints was proposed,and the fracture mechanism of the solders was also discussed.In the results,the tensile strength of the welded joints reaches 538.1 MPa at 140 A welding current,which is 95.3%and 97.4%of the tensile strength for PM HCCI and LCS,respectively.The microhardness of the welded joints decreases from HCCI side to LCS side in the horizontal direction,whereas in the vertical direction,the microhardness distribution is of M-shape due to the secondary tempering and alloying element diffusion/segregation.The fusion zone(FZ)mainly consists of the austenite and tempered martensite at the welding current of 140 A,and there is a single austenite columnar crystals zone between FZ and LCS;while there is a HCCI columnar crystal zone between FZ and the sintered HCCI,in which the coarsen carbides with branches are distributed along the matrix’s grain boundary.

关 键 词：高铬铸铁 手工钨极氩弧焊 异种金属焊接 焊接性能 微观结构 抗拉强度 显微硬度 

分 类 号：TF125[冶金工程—粉末冶金] TG47[冶金工程—冶金物理化学]