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金属学报  2018, Vol. 54 Issue (12): 1735-1744    DOI: 10.11900/0412.1961.2018.00151
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镁合金焊缝液化裂纹敏感性及预测方法探究
陈树君, 王宣, 袁涛(), 李晓旭
北京工业大学机电学院汽车结构部件先进制造技术教育部工程研究中心 北京 100124
Research on Prediction Method of Liquation Cracking Susceptibility to Magnesium Alloy Welds
Shujun CHEN, Xuan WANG, Tao YUAN(), Xiaoxu LI
Engineering Research Center of Advanced Manufacturing Technology for Automotive Components, Ministry of Education, Beijing University of Technology, Beijing 100124, China
全文: PDF(10112 KB)   HTML
摘要: 

以AZ31与AZ91镁合金为母材,AZ61与AZ92镁合金为填充焊丝,利用冷金属过渡焊接(CMT)方法进行横向拘束环行焊缝裂纹实验,探究AZ系列镁合金部分熔化区的液化现象,并结合液化裂纹产生机理提出一种定性判断镁合金液化裂纹敏感性的方法。结果表明,焊接过程中,AZ91镁合金焊缝边缘发生了γ (Mg17Al12)相与富Mg α相的共晶反应,产生了液相,形成了部分熔化区;在AZ31镁合金中不存在γ (Mg17Al12)相,液化现象不明显,部分熔化区较小。同时,提出了基于二元合金相图的镁合金液化裂纹敏感性判断方法,以判断镁合金母材和焊丝成分对焊缝部分熔化区液化裂纹敏感性的影响规律,即,母材为AZ91时的液化裂纹敏感性比母材为AZ31时更高,焊丝为AZ92时的液化裂纹敏感性较焊丝为AZ61时更低。

关键词 镁合金CMT-MIG液化裂纹敏感性预测化学成分    
Abstract

Magnesium alloys has a wide application prospect due to their good properties, such as high specific strength and specific stiffness, but the susceptibility of liquation cracking is also pretty high. The liquation in partially melted zone of AZ-series magnesium alloys were investigated with circular-patch welding test. The AZ91, AZ31 base alloys were welded with AZ61 and AZ92 filler wires by using the cold metal transter metal inert-gas (CMT-MIG) welding. The results show that, the liquation occurred along the weld edge of AZ91 with the eutectic reaction occurring between γ (Mg17Al12) phase and Mg-rich phase. The liquation susceptibility of AZ31 was pretty low as γ (Mg17Al12) was not present in base metal of AZ31. Meanwhile, a new method for predicting liquation cracking based on binary phase diagram was proposed. When the initial solidification temperature of weld is higher and the solidification temperature range of weld is shorter than those of base metal, the liquation crack susceptibility of weld is mostly higher. When the initial solidification temperature of weld is close to or below that of base metal, and the solidification temperature range of weld is close to or longer than that of base metal, the liquation cracking susceptibility of weld is lower. This method worked well on predicting the effect of composition of base metal and filler wires on liquation cracking, and the predicting results are consistent with the experimental results. That is, the liquation cracking susceptibility is higher with AZ91 base metal used than that with AZ31 base metal. And, the liquation cracking susceptibility is lower with AZ92 filler wire than that with AZ61 filler wire.

Key wordsmagnesium alloy    CMT-MIG welding    liquation cracking    susceptibility prediction    chemical composition
收稿日期: 2018-04-19     
ZTFLH:  TG401  
基金资助:国家自然科学基金项目No.51704013,北京市教委科研计划一般项目No.KM201810005016和中国博士后科学基金项目No.2016M600881
作者简介:

作者简介 陈树君,男,1971年生,教授,博士

引用本文:

陈树君, 王宣, 袁涛, 李晓旭. 镁合金焊缝液化裂纹敏感性及预测方法探究[J]. 金属学报, 2018, 54(12): 1735-1744.
Shujun CHEN, Xuan WANG, Tao YUAN, Xiaoxu LI. Research on Prediction Method of Liquation Cracking Susceptibility to Magnesium Alloy Welds. Acta Metall Sin, 2018, 54(12): 1735-1744.

链接本文:

https://www.ams.org.cn/CN/10.11900/0412.1961.2018.00151      或      https://www.ams.org.cn/CN/Y2018/V54/I12/1735

图1  横向拘束环形焊缝裂纹实验装置
Material Alloy Al Zn Mn Mg
Workpiece/patch AZ31 3.0 1.0 0.6 Bal.
AZ91 9.0 0.7 0.2 Bal.
Filler wire AZ61 6.5 1.0 0.3 Bal.
AZ92 9.0 2.0 0.3 Bal.
表1  待焊试件及填充焊丝化学成分
图2  横向拘束环形焊缝裂纹实验待焊试件示意图
Weld # Workpiece Patch Filler wire Wire speed / (mmin-1) Current / A Travel speed / (mmin-1)
1 AZ31 AZ31 AZ61 7.0 89 0.36
2 AZ92 7.0 98 0.36
3 AZ91 AZ91 AZ61 7.0 90 0.36
4 AZ92 7.0 89 0.36
5 AZ91 AZ31 AZ61 7.0 87 0.36
6 AZ92 7.0 87 0.36
7 AZ31 AZ91 AZ61 7.0 98 0.36
8 AZ92 7.0 90 0.36
表2  镁合金横向拘束环形焊缝裂纹实验参数
图3  3号焊缝截面微观组织及EDS
图4  1号焊缝截面微观组织及EDS
图5  镁合金焊缝熔合区液化裂纹产生机制示意图
图6  A-B二元相图
图7  镁合金横向拘束环形焊缝上表面宏观形貌
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