文献类型：期刊文献

英文题名：Microstructure and Mechanical Properties of a Fiber Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

作者：Xie, Miao-Xia[1];Li, Yan-Xin[1];Shang, Xiang-Tao[1];Wang, Xue-Wu[2];Pei, Jun-Yu[3]

机构：[1]Xian Univ Architecture & Technol, Sch Mech & Elect Engn, Xian 710055, Shaanxi, Peoples R China;[2]East China Univ Sci & Technol, Sch Informat Sci & Engn, Shanghai 200237, Peoples R China;[3]Xi An Jiao Tong Univ, State Key Lab Mech Behav Mat, Xiann 710049, Peoples R China

年份：2019

卷号：9

期号：6

外文期刊名：METALS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000475356500024)】；

基金：This work was supported by the National Natural Science Foundation of China (Grant No. 51775416 and 61773165).

语种：英文

外文关键词：high-performance molybdenum alloy; fiber welding; heat input; microstructure; mechanical properties; grain boundary segregation

摘要：Fiber welding of socket-joints made of nanostructured high-performance molybdenum alloy (NS Mo) was carried out to get a better understanding of the role of welding heat input. It was found that low heat input (i.e., high welding speed) resulted in significantly refined grains in the fusion zone (FZ) of fiber laser welded NS Mo joints. When welding heat input decreased from 3600 J/cm (i.e., 1.2 kW, 20 cm/min) to 250 J/cm (i.e., 2.5 kW, 600 cm/min), the tensile strength of welded joints increased from about 250 MPa to about 570 MPa. It was confirmed by energy spectrum analysis that the higher the welding heat input, the higher the oxygen contents at the grain boundary (GB) within the FZ. In addition, the most important reason for poor strength of welded joints of Mo alloys was reported as being that MoO2 was segregated on the grain boundary. Therefore, it was concluded that welding under low heat input (i.e., high welding speed) was able to reduce the segregation degree of MoO2 at the grain boundary by refining grains and increasing the total area of GBs, thus improving the strength of welded joints and reducing the proportion of the intergranular fracture zone in tensile fractures.