根部间隙及热处理对7075Al合金AC-CMT焊接头组织及性能的影响

doi:10.11896/cldb.25030013

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Abstract The 7075Al alloy has been widely used in various industrial fields such as aerospace, rail transportation, petroleum and petrochemical industries due to its excellent mechanical properties and corrosion resistance. However, this alloy is considered to be poor weldability with conventional arc welding because of its high cracking susceptibility and great decrease in strength and corrosion properties of the welded joint. In thiswork, 3 mm thick 7075Al alloy was AC-CMT arc welded with customized 7075Al alloy welding wire and I-shaped groove. The effects of root gap and heat treatment on the microstructure and properties of the joint were studied. The results showed that the weld formation was excellent without any cracks in internal parts of the weld, except for crater cracks occasionally observed in the arc extinguishing end. With the root gap increasing from 2 mm to 3 mm, the arc length and arc root diameter decrease due to its plunging into the gap, and the arc voltage decreases. The front weld width decreases while the back weld width increases. The grain in the central zone of the weld is slightly coarsened, while the grain near the fusion line in both the weld and HAZ is refined. The morphology of eutectic T-phase precipitated at the grain boundary changes from strip to globular shape, with a decrease in size. The tensile strength and elongation of the joint increase remarkably. After heat treatment, the strip-shaped T-phase in the weld metal with a 3 mm gap basically disappears, while there is still a small amount of strip-shaped T-phase in the weld metal with a 2 mm gap. The tensile strength of welded joints with individual root gaps significantly increases, while that of the welded joint with 3 mm root gap increases more significantly, reaching the tensile strength of the base material.

Key words： AC-CMT arc welding root gap grain size tensile strength

Published: Online: 2026-04-16

CLC number:

TG442

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	Articles by authors
	WANG Kekuan
	LIU Jian
	CUI Wanting
	ZHANG Bo
	ZHANG Baojun
	LI Liangyu
	NIU Huli

Cite this article:

WANG Kekuan,LIU Jian,CUI Wanting, et al. Effect of Root Gap and Heat Treatment on Microstructure and Properties of AC-CMT Arc Welded 7075Al Alloy Joint[J]. Materials Reports, 2026, 40(7): 25030013-7.

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https://www.mater-rep.com/EN/10.11896/cldb.25030013 OR https://www.mater-rep.com/EN/Y2026/V40/I7/25030013

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