Transactions of FAMENA, Vol. 50 No. 2, 2026.
Original scientific paper
https://doi.org/10.21278/TOF.502080825
Investigation of Microstructure and Mechanical Properties of Cold Metal Transferwelded AA7075 Joints
R. Venkatesh
orcid.org/0009-0002-4920-9860
; Research Scholar, Department of Mechanical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Chennai-603110, India; Assistant Professor, Department of Mechanical Engineering, DMI College of Engineering, Chennai-600124, India
K. Jayakumar
orcid.org/0000-0003-2482-981X
; Associate Professor, Department of Mechanical Engineering,Sri Sivasubramaniya Nadar College of Engineering, Chennai-603110, India
*
* Corresponding author.
Abstract
This study investigates the mechanical performance and microstructural evolution of AA7075 aluminium alloy joints produced using the cold metal transfer process. Owing to its low heat input, cold metal transfer is well suited for welding heat-sensitive precipitation-hardened alloys prone to porosity, hot cracking, and strength loss. Response surface methodology with a central composite design was applied to quantify the effects of welding current (160 to 200 A), welding speed (100 to 140 mm/min), and wire feed speed (1000 to 2000 mm/min) on ultimate tensile strength. The resulting empirical model showed strong statistical significance and close agreement between predicted and experimental values. Microstructural analysis revealed the dissolution of dizinc magnesium precipitate, dendritic solidification, and inter-dendritic segregation in the fusion zone; partial over-ageing in the heat-affected zone; and the retention of the T6 structure in the base metal. Hardness decreased from 164–171 HV0.5 (the base metal) to 147–155 HV0.5 (the heat-affected zone) and 140–145 HV0.5 (the fusion zone). Validation using optimised parameters achieved an ultimate tensile strength of 366 MPa, matching the model prediction. Overall, the study confirms cold metal transfer as an effective technique for producing high-strength AA7075 welds with minimal thermal damage.
Keywords
AA7075; Cold metal transfer; Welding parameters; Response surface methodology; Microstructure; Hardness; Tensile strength
Hrčak ID:
347682
URI
Publication date:
9.4.2026.
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