7150鋁合金熱變形行為及微觀組織Flow Stress Behavior and Microstructure of 7150 Aluminum Alloy during Hot Deformation

采用Gleeble熱模擬機(jī)進(jìn)行熱壓縮實(shí)驗(yàn),研究7150鋁合金在變形溫度為300~450℃、應(yīng)變速率為0.01~10s^-1條件下的變形行為,采用Zener-Hollomon參數(shù)法構(gòu)建合金高溫塑性變形本構(gòu)方程,并對變形后的微觀組織進(jìn)行分析。研究表明:7150鋁合金的流變應(yīng)力隨應(yīng)變速率增大而增大,隨變形溫度增大而降低。該合金熱壓縮變形的流變應(yīng)力行為可用雙曲正弦形式的本構(gòu)方程描述,其參數(shù)A為4.161×10¹⁴ s^-1,α為0.01956 MPa^-1,n為5.14336,熱變形激活能Q為229.7531kJ/mol。隨著溫度升高和應(yīng)變速率降低,動(dòng)態(tài)再結(jié)晶逐漸取代動(dòng)態(tài)回復(fù)成為合金的主要軟化機(jī)制。

The flow stress behavior and the deformation microstructure of 7150 aluminum alloy during hot compression deformation were studied by thermal simulation test using Gleeble thermal simulation machine at temperature ranging from 300℃ to 450℃ and strain-rate from 0.01s^-1 to 10s^-1. The constitutive equation of the plastic deformation of 7150 alloy at elevated temperature was obtained by introducing Zener-Hollomon parameter. The experimental results indicate that the flow stress and peak stress increase with increasing strain rate, and decrease with increasing deformation temperature, which can be described by a constitutive equation in hyperbolic sine function, whose values of related parameters A,α, n and activation energy for hot deformation Q, are 4.161×10¹⁴ s^-1, 0.01956 MPa^-1, 5.14336 and 229.7531kJ/mol respectively. With increasing the temperature and decreasing the strain rate, the main soften mechanism of the 7150 alloy transforms from dynamic recovery to dynamic re-crystallization.