Influence of post weld heat treatment on the tensile and microhardness characteristics of friction stir welded joints of AA6082/ZrO2/B4C composites

Abstract

In this recent work, the influence of post weld heat treatment (PWHT) on the tensile strength and microhardness characteristics of friction stir (FS) welded joints of AA6082/ 3 wt% ZrO2/ 5 wt% B4C composites is investigated. PWHT is performed on FS welded AA6082/ 3 wt% ZrO2/ 5 wt% B4C composites in order to improve the microhardness (WNH) and ultimate tensile strength (UTS). The heat treatment employed is the solution treatment followed by ageing. PWHT process is performed by solutionizing FS welded AA6082/ 3 wt% ZrO2/ 5 wt% B4C composites at 450 °C for a soaking period of 1 h followed by water quenching and ageing at 120 °C for a soaking period of 24 h. PWHT is carried out on the FS welded composites at a welding condition during which a medium amount of heat input is considered and its effect on microstructure, UTS and microhardness of FS welded joints are analyzed. The experimental results confirm that the PWHT ominously influences the UTS and microhardness characteristics of the FSW joints. It is found that microhardness obtained after PWHT for the medium heat input of 57.11 kJ/mm is 112.6 HV and this is about 20% increase in the microhardness as compared to corresponding FS welded AA6082/ 3 wt% ZrO2/ 5 wt% B4C sample before PWHT. It is also found that UTS obtained after PWHT is 253 MPa and there is an increase of 0.8 % UTS as compared to corresponding FS welded AA6082/ 3 wt% ZrO2/ 5 wt% B4C sample before PWHT.