MATERIALS
Comparative study of hardness evolution in 5754 aluminum welds under AC and DC welding currents
This study examines how thermal and mechanical effects influence hardness distribution in 4, 6, and 8 mm AA5754 aluminum plates welded using TIG with AC and DC currents. Vickers hardness (HV0.01) was measured alongside tensile tests to evaluate weld performance. Results show that AC welding produces higher but more variable hardness, while DC welding yields more stable profiles. Notably, thinner plates (4 mm) showed minimal hardness differences between current types due to faster cooling. Strain hardening increased hardness up to 125 HV and reduced variation. The extent of hardness stabilization and heat-affected zone size depended on plate thickness. Although current type influenced hardness distribution, it had little effect on fracture toughness.