Effect of hot rolling on microstructure and properties of the ZEK100 alloy

Abstract

Abstract Attempts to expand manufacturing capabilities of magnesium-based sheet materials are described. The as-cast ZEK100 (Mg 1.2Zn 0.35Zr 0.17Nd, in wt%) magnesium alloy was subjected to hot rolling at temperatures from 350 oC to 450 oC using the laboratory 50 ton reversible mill with preheated rolls to manufacture the 1.5–1.7 mm thick sheet. The rolling temperature affected the sheet properties and an increase in the rolling temperature from 250 to 450 oC caused reduction of tensile strength from 257 to 228 MPa accompanied by a reduction in tensile yield stress from 237 to 185 MPa. At the same time, the alloy elongation increased from 17 to 21%. For the same rolling temperature range, the compressive strength reduced from 418 to 351 MPa. The post-rolling annealing at 450 oC led to reduction of both tensile and compressive properties with the largest changes corresponding to the rolling temperature of 350 °C. The correlation between the alloy grain size after rolling and the sheet properties was established where a reduction in grain size was accompanied by an increase of both the tensile/compressive strength and yield stress. Based on Hall–Petch relationship and an average grain size the correlation developed in this study may be used as the prediction model for properties of the hot rolled magnesium sheet. The results are discussed in terms of recent developments in magnesium sheet alloys and the vital role played in this process by rare earth elements.