Study of Microstructure and Mechanical Properties of 7075 Aluminum Alloy FSW Joints

LI Zhiqiang; FEI Shangcai

doi:10.7512/j.issn.1001-2303.2026.02.12

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Study of Microstructure and Mechanical Properties of 7075 Aluminum Alloy FSW Joints
Vol. 56, Issue 2, Pages: 103-111(2026)
Received：08 April 2025，

Revised：2025-10-15，

Published：20 February 2026
DOI： 10.7512/j.issn.1001-2303.2026.02.12
稿件说明：

移动端阅览

李志强，飞尚才.7075铝合金FSW接头组织及力学性能研究［J］.电焊机，2026，56（2）：103-111. DOI： 10.7512/j.issn.1001-2303.2026.02.12.

LI Zhiqiang, FEI Shangcai.Study of Microstructure and Mechanical Properties of 7075 Aluminum Alloy FSW Joints[J].Electric Welding Machine, 2026, 56(2): 103-111. DOI： 10.7512/j.issn.1001-2303.2026.02.12.

摘要

以搅拌头转速（

）和焊接速度（

）为变量，对6 mm厚7075-T6铝合金板材进行搅拌摩擦焊接试验，研究不同焊接参数下焊缝形貌、显微组织、力学性能的变化规律。结

果表明，焊接速度100 mm/min时，

在600~1 400 r/min范围内焊缝均可成形；搅拌头转速800 r/min时，

在60~120 mm/min范围内焊缝均可成形。焊接接头BM是由再结晶组织和变形板条状组成的轧制组织，WNZ晶粒与强化相细小且分布均匀，形成典型“洋葱环”形貌，TMAZ在板条状组织内形成了回复晶粒组织，AS分界明显；WNZ、TMAZ晶粒大小与

呈正相关，与

呈负相关。接头硬度分布呈倒“M”形，焊缝区硬度较母材减小，最小值在RS侧TMAZ和HAZ过渡处，WNZ平均硬度分布随着

、

的增大呈先增大后降低的变化趋势；接头抗拉强度和伸长率，整体分布呈“镰刀”形，与

呈正相关，与

呈负相关。为获得焊缝成形良好、无明显缺陷，力学性能优良的焊接接头，需大的搅拌头转速配合小的焊接速度，

值应在10以上。

Abstract

Friction stir welding (FSW) experiments were conducted on 6 mm thick 7075-T6 aluminum alloy plates

with the rotational speed (

) and welding speed (

) as variables

to investigate the effects of welding parameters on weld morphology

microstructure

and mechanical properties. The results indicate that sound welds can be achieved within a rotational speed range of 600-1400 r/min at a constant welding speed of 100 mm/min

and within a welding speed range of 60-120 mm/min at a constant rotational speed of 800 r/min. The base material (BM) exhibits a rolled structure comprising recrystallized grains and deformed elongated grains. In the weld nugget zone (WNZ)

fine and uniformly distributed grains and strengthening phases form a typical “onion ring” structure. The thermo-mechanically affected zone (TMAZ) shows recovered grain structures within the elongated grains

with a distinct boundary on the advancing side (AS). The grain sizes in both the WNZ and TMAZ are positively correlated with the rotational speed (

) and negatively correlated with the welding speed (

). The microhardness profile across the joint exhibits a characteristic "inverted M" shape

with the weld zone being softer than the BM. The lowest hardness value is located at the transition between the TMAZ and the heat-affected zone (HAZ) on the retreating side (RS). The average hardness in t

he WNZ first increases and then decreases with increasing

and

. The tensile strength and elongation of the joints generally follow a "sickle-shaped" distribution trend

showing a positive correlation with n and a negative correlation with v. To produce defect-free joints with good formation and excellent mechanical properties

a higher rotational speed combined with a lower welding speed is recommended

with an

ratio preferably above 10.

关键词

Keywords

references

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