Optimization of Equal Channel Angular Pressing Parameters for Improving the Hardness and Microstructure Properties of Al–Zn–Mg Alloy by Using Taguchi Method

Abstract

In this study, optimization of equal channel angular pressing (ECAP) parameters was aimed to improve the mechanical and microstructure properties of Al–Zn–Mg alloy using the Taguchi method with ANOVA analysis. Three different parameters (process temperature, processing route, and the number of passes) with three different levels were examined so L9 (33) orthogonal array was employed. The effects of these parameters on the microstructure properties of Al–Zn–Mg alloy were studied using X-ray diffractometer, optical microscopy, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy and mechanical properties were measured by Vickers micro-hardness experimental tests. Among the samples obtained, the sample that meets the desired hardness and grain size value was characterized. The results indicate that eight pass ECAP in route Bc at 100 °C is found as a more appropriate condition that meets the highest micro-hardness value and the lowest grain size value. Microstructural investigations showed that grain size was highly affected by the temperature, and is less affected by the number of passes and ECAP routes. The results showed that the increasing ECAP temperature leads to a decrease in the fraction of HABs, an increase in the grain size and an increase in the equiaxed of the grains.