Effect of heat treatment after welding on microhardness and microstructures of aluminum-steel welding joints

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Effect of heat treatment after welding on microhardness and microstructures of aluminum-steel welding joints
Vol. 48, Issue 7, Pages: 85-90(2018)
Published：2018
DOI：
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DOI：

Effect of heat treatment after welding on microhardness and microstructures of aluminum-steel welding joints[J]. Eletric Welding Machine2018, 48(7): 85-90. DOI：

摘要

选用脉冲旁路耦合电弧焊以ER4043铝合金丝作为填充材料进行铝/钢异种金属的搭接焊

焊接接头分别在270℃和350℃下进行焊后热处理。采用扫描电镜观察焊接接头微观组织

使用能谱仪和显微硬度测试仪测试热处理前后焊接接头不同区域合金元素的扩散情况和硬度分布情况。结果表明:焊后热处理会使焊接接头中的合金成分产生均匀化扩散

350℃热处理后焊接接头焊趾区生成了一层金属间化合物Fe

0.4

;270℃热处理后焊接接头焊缝金属组织的硬度分布均匀

焊趾区组织硬度变化较小

这有利于防止焊接接头产生应力集中、提高焊接接头的力学性能。

Abstract

Dissimilar metals of 1060 aluminum and galvanized steel were joined with lap joint by pulsed double electrode gas metal arc welding-brazing with ER4043 aluminum filler metals. The welding joints of aluminum and steel were heat-treated at 270 ℃ and 350 ℃. The microstructure of the welded joint was observed by scanning electron microscopy

the diffusion and hardness distribution of alloying elements in different areas of the welded joint before and after heat treatment were tested by energy spectrometer and microhardness tester. The results show that the homogenization diffusion of alloy elements in welding joint occurs after heat treatment.After heat treatment at 350 ℃

a layer of Fe

0.4

intermetallic compound was formed in the weld toe area of the welding joint. The microhardness distribution of weld metal is uniform and the change of microhardness of weld toe area is smaller after heat treatment at 270 ℃

it is beneficial to avoid the stress concentration and improve the mechanical properties of the welding joint.