Mechanical and microstructural analysis of the Gleeble-simulated HAZ in the 6082-T6 MIG-welded aluminum alloy

Abstract

This novel study investigates the heat-affected zone (HAZ) of 6082-T6 plates with Y grooves. The thermal history of various points was collected, and three points in the HAZ subzones were chosen based on the simulation of the weld, peak temperatures of which ranged from 345°C to 615°C. These subzones were subsequently simulated in the Gleeble furnace. Quasi-static tensile testing where digital image correlation (DIC) analysis was employed indicated the weakened HAZ with a variation in the mechanical properties across the area. Vicker’s hardness test was mapped across the Gleeble samples and the original joint where similarities were observed. Microstructural analysis was conducted utilizing optical (OM) and scanning electron microscopy (SEM), and chemical composition was obtained via an EDS detector.

A correlation between the different methodologies was established. It was highlighted that the subzone closest to the weld fusion line exhibited partial hardness recovery owing to the reprecipitation of hardening phases. In contrast, in the other two subzones, the yield strengths deteriorated in correlation with their average grain size, which is in agreement with the Hall-Petch equation. The Gleeble-simulated sample of the subzone farthest from the fusion line indicated the lowest ultimate tensile strength and highest elongation at break.