Investigation on the impact of B4C content in AA5052 based metal matrix composites on the mechanical properties of welded joints

Abstract

In this research, the tungsten inert gas welding was used to join together metal matrix composites (MMCs) reinforced in different percentages with B4C. The welding settings were maintained at a constant value for all specimen situations. Thermal ageing was used to achieve maximum age-hardening in the welded composites. Misorientation and energy storage are the microscopic features of aged composites that distinguish them from composites that have not been aged. Tensile strength and hardness both increased with increasing B4C concentration, but at opposite rates, suggesting that hardness resulted from energy storage while tensile strength resulted from misorientation. Age hardening as measured by electron backscatter diffraction (EBSD) occurs due to a active recovery of the weld metal (WM) region following a reorganization in displacement structures caused by the precipitation of magnesium silicate or an increase in boron carbide content. The healing process is primarily driven by the action of precipitation strengthening, rather than the impact of obliteration of displacements, as evidenced by the correlation between tensile strength and reduction in misorientation. Adding B4C to aluminium metal matrix composites before welding causes the structural changes that need to be characterized. The welding process's structural changes are analysed, and connections are made to the welded junctions' mechanical behaviour. The study's findings suggest that the microstructure's misorientation distribution is as crucial as the average amount of misorientation in determining a material's strength.