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What Common Welding Defects Shall Be Avoided in Welding Aluminum Plates and Nickel Sheets with Aluminum Diffusion Welder?

Sep 10,2026

Dissimilar‑metal welding of aluminum plates and nickel sheets by aluminum diffusion welders is a widely‑adopted process for new‑energy conductive connecting parts. It realizes inter‑penetration and bonding of metal atoms under high temperature and high pressure.

Nevertheless, aluminum and nickel have great differences in material properties. Aluminum tends to oxidize, is relatively soft and prone to thermal deformation; nickel sheets feature high hardness, high‑temperature resistance and are easy to oxidize and discolor under high‑temperature conditions.

I Process Difficulties of Aluminum‑Nickel Diffusion Welding

Oxide films readily form on aluminum‑plate surfaces and block metal fusion, which constitutes the major cause of cold joints and pores. The two metals differ greatly in hardness and expansion coefficient. Internal stress easily generates during welding and cooling, leading to warping and delamination. Excessively long high‑temperature holding time makes weld spots brittle, prone to fracture under later‑stage vibration and bending.

II Common Welding Defects, Causes and Avoidance Measures

1.Interfacial cold joints and delamination‑peeling

Main causes: oxide films, oil stains and impurities on workpiece surfaces are not thoroughly cleaned, forming barrier layers; poor fitting of workpieces before welding with inter‑layer gaps; insufficient welding pressure and inadequate holding time so that metal atoms cannot fully inter‑diffuse and bond.

Avoidance: Polish and clean mating surfaces of aluminum plates and nickel sheets before welding to remove oxide scale and stains and guarantee clean metal‑to‑metal contact; match proper pressure and holding duration to realize sufficient inter‑diffusion bonding of the two metals.

2.Interfacial micro‑pores and inter‑layer cavities

Main causes: residual moisture and oil stains on workpiece surfaces vaporize at high temperature to generate gas; air trapped in fitting gaps fails to be fully exhausted and temperature rises too fast.

Avoidance: Complete drying, degreasing and dedusting for workpieces before welding; adopt slow temperature‑rise and reserve exhaust time to guarantee dense and pore‑free weld interiors.

3.Crushed, thinned and deformed aluminum plates

Main causes: Aluminum is soft and easy to soften under high temperature; excessive welding pressure and over‑long holding time lead to over‑squeezing deformation of plates; uneven force‑bearing causes local crushing.

Avoidance: Adopt aluminum‑oriented welding process; refrain from blind pressure and temperature increase; prevent local crushing and preserve complete plate structure.

4.Blackened, warped and wrinkled nickel sheets

Main causes: Excessively high welding temperature and prolonged high‑temperature holding cause high‑temperature oxidation of nickel sheets; great difference in thermal‑shrinkage performance between the two metals generates uneven stress during cooling; offset workpiece placement and uneven mold surfaces.

Avoidance: Control welding temperature and holding duration to avoid excessive high‑temperature oxidation; ensure centered placement and tight fitting of workpieces, calibrate mold flatness periodically; perform slow cooling under pressure after welding to offset thermal‑cold shrinkage stress and prevent nickel‑sheet deformation and discoloration.

5.Brittleness of weld spots and fracture under bending or vibration

Main causes: Excessive temperature and over‑long holding time generate large amount of brittle inter‑metallic compounds at metal interfaces, making weld spots lose toughness and turn brittle.

Avoidance: Strictly cap upper‑limit temperature, cut redundant high‑temperature holding time and only ensure effective diffusion bonding; adopt gradient temperature‑rise‑and‑fall mode to reduce brittle‑phase generation and retain weld‑spot toughness and vibration‑resistance.

6.Unstable batch quality, resistance drift and later‑stage delamination

Main causes: Inconsistent pre‑welding cleaning standards and varying degrees of oxidation and contamination; temperature‑pressure drift of equipment during production; mold wear and carbon‑deposit resulting in unstable force‑bearing; incomplete release of welding residual stress.

Avoidance: Unify standards for pre‑welding cleaning, stacking and placement; solidify welding process parameters; clean and calibrate molds periodically and compensate for equipment temperature‑pressure deviation; optimize welding time‑sequence to release welding stress.

Wuxi Haifei Intelligent Equipment Co., Ltd. https://www.haifeiwelder.com/

Wuxi Haifei Intelligent Equipment Co., Ltd. has been focusing on the R&D and production of diffusion‑welding equipment for 17 years. The company has passed ISO9001 Quality Management System Certification, China Compulsory Certification (3C) 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, and a Gazelle Enterprise in the Southern Jiangsu National Self‑Dependent Innovation Demonstration Zone.

Should you be interested in our diffusion‑welding equipment, please contact us: 400‑0510‑750.