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<p>The current research explores weldability, mechanical strength, and microstructural features of aluminum alloys, AA6082 and AA7075, welded through the Cold Metal Transfer (CMT) process. The welded joints are sliced into different coupons to investigate the HAZ width, microstructural changes, welding strength, and corrosion resistance. For CMT welding, sample 1 was processed with a 140&#xa0;A current, a welding speed of 300&#xa0;mm/min, and a wire feed rate of 4000&#xa0;mm/min, whereas sample 2 used a 150&#xa0;A current, a welding speed of 400&#xa0;mm/min, and a wire feed rate of 5000&#xa0;mm/min. The bead geometry of the weld and the dimensions of the heat-affected zone (HAZ) were assessed using an optical microscope. Microstructural examination showed a finer grain structure, decreased segregation, and a more even distribution of strengthening precipitates in the weld region, especially for sample 1. The hardness and uniaxial tests were conducted on Izod and universal testing machines, respectively. They recorded increased values in the weld region, with a pronounced decrease in the HAZ, consistent with the observed failure positions in tensile testing. Sample 1 had better mechanical properties, as evidenced by an ultimate tensile strength (UTS) of 225&#xa0;MPa and impact energy of 34&#xa0;J due to its more refined weld microstructure and lesser HAZ softening. On the other hand, sample 2, which had a larger HAZ and coarse grain structure, had lesser strength and toughness. Electrochemical corrosion tests in 3.5 wt% NaCl solution indicated that the weld zone had better corrosion resistance than the HAZ, with sample 1 having comparatively better performance owing to lower phase dissolution and grain boundary precipitation under control. Tensile and impact fractography, combined with SEM/EDAX, showed that the CMT‑welded AA6082–AA7075 joint failed predominantly by micro‑void coalescence at coarsened intermetallic and oxide inclusions, yielding a UTS of 225&#xa0;MPa, 9% elongation, and an impact energy of 34&#xa0;J.</p>

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Cold Metal Transfer Welding of Dissimilar AA6082-AA7075 Alloys: Microstructure, Mechanical Properties, and Corrosion Resistance Assessment

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • L. Aslesha Chilakamarri,
  • Charan Rath Kali,
  • T. Vishnu Vardhan

摘要

The current research explores weldability, mechanical strength, and microstructural features of aluminum alloys, AA6082 and AA7075, welded through the Cold Metal Transfer (CMT) process. The welded joints are sliced into different coupons to investigate the HAZ width, microstructural changes, welding strength, and corrosion resistance. For CMT welding, sample 1 was processed with a 140 A current, a welding speed of 300 mm/min, and a wire feed rate of 4000 mm/min, whereas sample 2 used a 150 A current, a welding speed of 400 mm/min, and a wire feed rate of 5000 mm/min. The bead geometry of the weld and the dimensions of the heat-affected zone (HAZ) were assessed using an optical microscope. Microstructural examination showed a finer grain structure, decreased segregation, and a more even distribution of strengthening precipitates in the weld region, especially for sample 1. The hardness and uniaxial tests were conducted on Izod and universal testing machines, respectively. They recorded increased values in the weld region, with a pronounced decrease in the HAZ, consistent with the observed failure positions in tensile testing. Sample 1 had better mechanical properties, as evidenced by an ultimate tensile strength (UTS) of 225 MPa and impact energy of 34 J due to its more refined weld microstructure and lesser HAZ softening. On the other hand, sample 2, which had a larger HAZ and coarse grain structure, had lesser strength and toughness. Electrochemical corrosion tests in 3.5 wt% NaCl solution indicated that the weld zone had better corrosion resistance than the HAZ, with sample 1 having comparatively better performance owing to lower phase dissolution and grain boundary precipitation under control. Tensile and impact fractography, combined with SEM/EDAX, showed that the CMT‑welded AA6082–AA7075 joint failed predominantly by micro‑void coalescence at coarsened intermetallic and oxide inclusions, yielding a UTS of 225 MPa, 9% elongation, and an impact energy of 34 J.