On the Role of Experimental Variables in the Repetitive Corrugation and Straightening of an Al-Mg Alloy

Abstract

Abstract Microstructural and mechanical properties are highly influenced by strain homogeneity (or its absence) during severe plastic deformed materials. Strain inhomogeneity arises due to various parameters such as die profile, pressing velocity and working temperature. In this research, Al-Mg alloy is processed by repetitive corrugation and straightening (RCS). Three different die profiles such as V- shaped, Flat- and semi-circular grooves were used to study the effects of die profile on microstructural changes. With each die profile, the aluminium alloy was allowed to deform up to the maximum number of passes possible before the appearance of surface cracks. The imparted strain as a function of the die profile is estimated numerically and experimentally and compared. Also, the microstructures and mechanical properties are correlated with the imparted strain. From the results, it is clear that the flat groove die improves the mechanical properties significantly. In addition, the grain refinement in this case is good compared with that with the other two dies. The average grain size is reduced to 20 microns from 45 microns at the end of 8 passes with the flat groove die. The influence of temperature and pressing velocity during the RCS process was studied at two different temperatures (RT, 300 °C) and with two different pressing velocities (0.5 mm/s and 2 mm/s). The flat-groove die was used to process the material at these conditions. The strain imparted after every pass was measured experimentally and compared with the numerical value computed. Also, the mechanical properties such as strength and hardness were compared for the different conditions. The alloy processed at RT and the lower pressing velocity exhibits good mechanical properties. At the end of 8 passes, the grain size had decreased to 17 microns and 11 microns, respectively, from an average starting grain size of 45 microns in case of the pressing velocities of 2 mm/s and 0.5 mm/s.