Effects of pre-deformation and heat treatment conditions in the SIMA process on properties of an Al–Zn–Mg–Cu alloy modified by Al–8B grain refiner

This study was undertaken to investigate the influence of Al–8B master alloy on the structural characteristics and hardness values of Al–12Zn–3Mg–2.5Cu aluminum alloy. The optimum amount of B containing master alloy for proper grain refining was selected as 3.75 wt.%. The alloy was produced by modified strain-induced melt activation (SIMA) process. Reheating condition to obtain a fine globular microstructure was optimized. Results indicated that with the increase of strain, sphericity of particles increases, their size decreases and sphericity takes place in less reheating time. By increasing of the holding time at 590 °C, an increase in the shape factor and a decrease in the globule size of the samples predeformed up to 60% were observed. Optimum combinations of average globule size and shape factor were obtained in holding time of 20 min. The hardness test results of the alloy also revealed that T6 heat treatment is more effective in hardness enhancement of all specimens in comparison with SIMA processing.