文献类型：期刊文献

英文题名：Effect of Heat Input on Porosity Defects in a Fiber Laser 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, Xian 710049, Peoples R China

年份：2019

卷号：12

期号：9

外文期刊名：MATERIALS

收录：;EI(收录号：20192106947354);WOS:【SCI-EXPANDED(收录号:WOS:000469757500074)】；

基金：This work was supported by the National Natural Science Foundation of China [Nos. 51775416 and 61773165].

语种：英文

外文关键词：molybdenum alloy; fiber laser welding; heat input; porosity defects

摘要：Porosity defects are still a challenging issue in the fusion welding of molybdenum and its alloys due to the pre-existing interior defects associated with the powder metallurgy process. Fiber laser welding of end plug and cladding tube made of nanostructured high-strength molybdenum (NS-Mo) alloy was performed in this work with an emphasis on the role of welding heat input. The distribution and morphology of porosity defects in the welded joints were examined by computed tomography (CT) and scanning electron microscopy (SEM). Preliminary results showed that laser welding of NS-Mo under low heat input significantly reduced the porosity defects in the fusion zone. The results of computed tomography (CT) showed that when the welding heat input decreased from 3600 J/cm (i.e., 1200 W, 0.2 m/min) to 250 J/cm (i.e., 2500 W, 6 m/min), the porosity ratio of the NS-Mo joints declined from 10.7% to 2.1%. Notable porosity defects under high heat input were related to the instability of the keyhole, expansion and the merging of bubbles in the molten pool, among which the instability of the keyhole played the dominant role. The porous defects at low heat input were generated as bubbles released from the powder metallurgy base metal (BM) did not have enough time to overflow and escape.