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How to Solve the Problem of Aluminum‑Alloy Bus‑Bar Cracking during Medium‑Frequency Spot‑Welding
Sep 22,2026
Aluminum‑alloy bus‑bars are widely adopted in new‑energy and energy‑storage industries. Medium‑frequency spot‑welding is often used for bus‑bar lap connection. Aluminum‑alloy material has low melting point, high thermal expansion coefficient and brittle intermetallic compounds are easy to generate during welding. Cracks including surface micro‑cracks, penetration cracks and heat‑affected‑zone cracks tend to appear on welding joints, which severely reduces mechanical strength and electrical conductivity of bus‑bar connecting positions.
I Root Causes of Aluminum‑Alloy Bus‑Bar Welding Cracks
1.Material property factor: Aluminum alloy has large thermal‑cold shrinkage difference, brittle intermetallic phases easily precipitate under rapid cooling condition after welding.
2.Welding heat‑input factor: Excessively high heat input leads to coarse grain and over‑burning; insufficient heat input causes incomplete fusion and high local stress. Both conditions will induce crack generation.
3.Stress‑strain factor: Unreasonable clamping mode generates large restraint stress at welding spot; uneven thermal expansion and contraction produce welding residual stress.
4.Surface‑condition factor: Oxide film, oil stains and impurities on bus‑bar mating surfaces hinder metallurgical bonding, create local stress concentration and trigger crack initiation.
5.Process‑sequence factor: Improper pressure time‑sequence, too‑fast pressure release after welding, the nugget is not fully solidified and shrinks under stress to form cracks.
II Practical Improvement Measures for Welding Cracks
1.Pre‑weld surface treatment: Fully remove surface oxide film, oil and impurities of lap joint area, guarantee clean metallurgical bonding interface.
2.Optimize welding heat‑input: Adopt moderate heat‑input parameter window; avoid over‑heat over‑burning and also avoid cold joint caused by insufficient energy.
3.Optimize pressure time‑sequence: Set reasonable pre‑pressing, welding pressure and post‑weld hold‑pressure duration; prohibit rapid pressure release before nugget complete solidification.
4.Optimize clamping and tooling: Adopt reasonable support and clamping tooling, reduce excessive constraint stress on welding zone.
5.Control welding cooling speed: Avoid ultra‑rapid cooling after welding, slow down cooling rate to restrain brittle phase precipitation.
6.Batch sampling inspection: Carry out appearance inspection, metallographic observation and tensile test on finished‑product welding spots to intercept hidden crack defects.
Wuxi Haifei Intelligent Equipment Co., Ltd. https://www.haifeiwelder.com/
Wuxi Haifei Intelligent Equipment Co., Ltd. has focused on the R&D and production of automated equipment for 17 years. The company has obtained ISO9001 quality management system certification, national 3C certification and CE certification. It is a National High-tech Enterprise, a Specialized, Refined, Differential and Innovative Enterprise of Jiangsu Province, a Specialized, Refined, Differential and Innovative Enterprise of Wuxi City, and a Gazelle Enterprise in Southern Jiangsu National Independent Innovation Demonstration Zone. Should you be interested in our automated equipment, please contact us: 400-0510-750
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Wuxi HAIFEI Intelligent Equipment Co., Ltd.
Wuxi HAIFEI Welding Equipment Co., Ltd.
Add: 28 Shuiyun Road, Yuecheng, Jiangyin, Jiangsu Province, China. (Postal Code: 214404)
Mobile: +86 18915302352
Email: wushijie@jshaifei.com