半固态铸造-叠轧深变形制备超细晶A2017合金

利用波浪型倾斜板半固态铸造和叠轧深变形的复合成形模式在等效应变为4.0的条件下制备出了平均晶粒为0.5μm的A2017合金超细晶材料.随着叠轧道次的增加,合金的维氏硬度先增后降,随后缓慢增加.在一定的退火温度下合金组织由亚稳定态向稳定态转变,在200℃保温1 h,晶粒生长比较缓慢,在退火温度高于200℃时晶粒变化明显;随着退火温度的升高,合金组织发生回复与再结晶过程,合金加工硬化逐渐消失,合金的维氏硬度降低.

Preparation of Ultra-fine Grain Alloy A2017 by Combining Semisolid Casting with Accumulative Roll-Bonding Process

The ultra-fine grain alloy A2017 was prepared the way the molten alloy A2017 was poured onto tilting corrugated board and then became two semisolid cast slabs for accumulative roll-bonding process to make them composite under the condition the equivalent strain was 4.0, of which the mean grain size was 0.5 p. During the accumulative roll-bonding process the Vichers hardness of workpieces increases then decreases and increases slowly once again along with the increasing number of passes. A2017's microstructure was transformed into stable state from metastable at a certain annealing temperature, i.e., the grain growth is slow at 200°C for 1 hour, while the grains grow obviously if the annealing temperature is higher than 200°C. The microstructure reveals static recovery/recrystallization process with increasing annealing temperature, and the effect of work hardening disappears gradually with Vichers hardness decreased.