Precipitates in the conventionally processed （solution treatment followed by aging） AZ80 alloy are coarse, cellular, and incoherent. They nucleate and grow on the basal planes of the matrix or distribute discontinuously in the alloy. Their unique morphology and undesired distribution make them ineffective for precipitation strengthening. This condition, however, can be modified by applying selected deforma-tion and heat treatment conditions. The effect of deformation and heat treatment on the morphology and distribution of precipitates has been studied. Deformation was introduced by hot extrusion, cold rolling, or equal channel angular pressing （ECAP）. The microstructures were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results showed that cold de-formation improved precipitation more significantly than hot deformation, and twinning promoted precipitation more effectively than slip. When ECAP was applied, the Bc-route induced more precipitates than the A-route.
Ping YangLi-na WangQing-ge yieJi-zhong LiHua DingLin-lin Lu
The mechanical property and forming limit experiments were carried out on a higli manganese TRIP/TWIP steels with manganese of 18.8%. And the forming /imit diagram was obtained. This hig：h manganese steel shows outstanding mechanical properties comhining high strength with good formability. Its limit plane strain corresponding to the lowest point in the plain strain condition is about 38%. The effects of conventional mechanical property on the limit plane strain were analyzed. With increasing the content of Mn, the limit plane strain increases, indicating that TWlP effect is advantageous to the increase of formability. Combining with three classical models and volume invaria ble principle, a FLD model was buih, which is suitable for high manganese steels very well.
