温間多軸鍛造AZ80-Fマグネシウム合金の組織と機械的性質

抄録

A hot extruded AZ80-F magnesium alloy was multi-directionally forged (MDFed) up to a cumulative strain of ΣΔε = 2.4 at warm temperatures of 543 K, 573 K and 593 K. Fine grained structures were gradually developed with increasing cumulative strain due to extensive occurrence of dynamic recrystallization. Bimodal grain size distribution tended to appear when MDFed to lower cumulative strain and/or at lower temperatures. The yield stress of the MDFed AZ80-F alloys with homogeneous grain size distribution followed the Hall-Petch relationship. MDFing to ΣΔε = 2.4 at 543 K exhibited the most excellent balance of mechanical properties of 260 MPa yield stress, 347 MPa tensile strength and 24％ elongation to fracture. The warm MDFed Mg alloys accepted additional 10％ cold rolling to cause further strengthening by strain hardening and sharp basal texture evolution.

Fig. 3 SEM-EBSD maps of the AZ80-F Mg alloys (a) hot-extruded (ΣΔε = 0) and MDFed at various conditions of (b) 543K-ΣΔε = 0.8, (c) 573K-ΣΔε = 0.8, (d) 593K-ΣΔε = 0.8, (e) 543K-ΣΔε = 2.4, (f) 573K-ΣΔε = 2.4 and (g) 593K-ΣΔε = 2.4. E.D. and F.A. indicate the extrude direction and the final forging axis, respectively.