Microstructure and mechanical properties of CMT joints for AZ31B magnesium alloy

ZHAO Yunfeng; HUO Qiaoying; TENG Dongping; FU Ningning

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Microstructure and mechanical properties of CMT joints for AZ31B magnesium alloy
Vol. 48, Issue 7, Pages: 31-35(2018)
DOI：

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ZHAO Yunfeng, HUO Qiaoying, TENG Dongping, et al. Microstructure and mechanical properties of CMT joints for AZ31B magnesium alloy. [J]. 48(7):31-35(2018)
DOI：

ZHAO Yunfeng, HUO Qiaoying, TENG Dongping, et al. Microstructure and mechanical properties of CMT joints for AZ31B magnesium alloy. [J]. 48(7):31-35(2018) DOI：

摘要

对厚度3 mm的挤压态AZ31B镁合金板材进行CMT对焊,焊接工艺参数为:直径1.6 mm WE-33M焊丝、送丝速度6 m/min、焊接电流76 A、焊接速度0.8 m/min、焊缝间隙1.5 mm,焊接过程稳定、无飞溅,焊缝成形良好。在此焊接工艺下对焊接接头的微观组织、显微硬度、力学性能和拉伸断口形貌进行了观察。结果表明,焊缝组织晶粒细小,焊缝区的显微硬度最高,平均约为86 HV,热影响区硬度约为62 HV,母材区的显微硬度约为65 HV。焊接接头最大抗拉强度为248.8 MPa,伸长率7.16%,分别为母材的96.7%和98.6%。断裂位置位于母材区,属于韧性断裂。

Abstract

3 mm thick AZ31B magnesium plates are butt welded by CMT technology. The welding parameters:1.6 mm diameter WE-33M feed wire,welding current of 76 A, wire feed rate of 6 m/min,welding speed of 0.8 m/min,weld interval of 1.5 mm. The welding process is stable without spatters and appearance of the weld is fine. The microstructure, microhardness,mechanical properties and tensile fracture appearance of welded joints are observed. The results show that grains in the weld microstructure are refined,the microhardness of the weld zone is the highest,and the average is 86 HV,the microhardness of HAZ is about 62 HV,the base metal about 65 HV. The maximum tensile strength and elongation of welded joint is 248.8 MPa and 7.16% respectively,which are 96.7%and 98.6% of the base metal respectively. The fracture is located in the base metal zone and belongs to ductile fracture.