Warm forming limits of rare earth-magnesium alloy ZEK100 sheet

Forming limit curves were developed for a rare earth-magnesium alloy, ZEK100-F, at temperatures between 25 and 350 A degrees C in both the rolling (RD) and transverse directions (TD) of the sheet. ZEK100-F contains additions of zirconium (Zr) as a grain refining alloying element and a rare earth addition, neodymium (Nd), that promotes a weakened basal texture allowing enhanced slip activity at lower temperatures. Warm formability measurements were also performed on non-rare earth containing AZ31B-O to examine the relative performance of these two alloys. The ZEK100 material exhibited significantly better room temperature formability over AZ31B-O with a limiting dome height of 29 mm for ZEK100 compared to only 12 mm for the AZ31B-O. At elevated temperatures (250 A degrees C) the difference in formability between the two alloys becomes less pronounced with a LDH of 40 and 36 mm for ZEK100 and AZ31B-O, respectively. What is particularly striking is the pronounced benefit of the rare earth alloyed material at intermediate temperatures, with an LDH of 37 mm at 150 A degrees C which equals the LDH of AZ31B at 250 A degrees C. Similar trends were determined in the measured forming limit curves reported here for the two alloys. The relative performance of the two alloys is largely attributed their initial textures. ZEK100-F also exhibits strongly anisotropic formability (RD versus TD) which can again be attributed to its' initial texture.