多道次热轧模拟过程中Al-Zn-Mg-Cu-Zr合金的再结晶特征

Recrystallization characterizations of an Al-Zn-Mg-Cu-Zr alloy during multi-pass hot rolling simulation

摘要:

采用Gleeble-1500D热模拟实验机根据设计的轧制工艺对7055合金进行多道次热压缩试验,模拟其企业热轧过程,采用电子背散射衍射和透射电镜研究了再结晶特征。在不同变形条件下,表现出不同的再结晶机制,主要动态再结晶机制有连续动态再结晶和几何动态再结晶。前者的形核机制主要为,原始晶界弓出形核和亚晶合并形核；后者归因于严重的不均匀变形。在道次间的间隙期间,静态再结晶发生。另外,尺寸大于1 μm的第二相也促进再结晶。

关键词:Al-Zn-Mg-Cu-Zr合金(AA7055);平面应变压缩;几何动态再结晶;第二相

Abstract:

In this paper we report recrystallization characterizations, using electron back-scattered diffraction (EBSD) and transmission electron microscope (TEM), of an Al-Zn-Mg-Cu-Zr alloy during multi-pass plain strain compression (PSC) performed to simulate the hot rolling system on Gleeble-l500D thermo-mechanical simulator．The results show that with increase of the deformation, there are mainly two dynamic recrystallization mechanisms responsible for the development of new grain, including continuous dynamic recrystallization (CDRX) and geometry dynamic recrystallization (GDRX). The former is related to original grain boundaries bulging and sub-grain coalescence. The latter can be associated with serious deformation inhomogeneity. Besides, SRX happens during inter-pass time. The particles with a size of more than 1 μm also result in the recrystallization.

Key words:Al-Zn-Mg-Cu-Zr alloy (AA7055); plain strain compression (PSC); geometry dynamic recrystallization; the second phase