材料期刊网

采用双道次热压缩实验,研究了新型Al-Zn-Mg-Cu高强铝合金铸态试样在温度300~400 ℃,应变速率0.01~0.1 s-1,变形程度33%+20%,保温0~900 s静态回复过程中的流变应力行为.结果表明:温度对该合金静态回复力学行为影响显著;(1)300 ℃和330 ℃温度较低时,变形过程中回复较慢,存储的变形能较高,保温期间的回复和再结晶使第二道次流变应力降低,表现为流变应力软化现象,且随着道次间保温时间的延长应力的软化程度增大;保温过程中析出相的出现减缓了应力软化速率;(2)温度升高到360 ℃和400 ℃时,变形过程中回复充分,存储的变形能低;变形保温后基体的固溶度高,第二道次流变应力升高,表现为流变应力硬化现象;360 ℃变形保温期间的回复/再结晶使得随着道次间保温时间的延长应力又逐渐降低软化,析出相减缓了应力的软化速率;而400 ℃变形保温期间没有回复/再结晶和析出相,所以硬化后的应力并不随着道次间保温时间的延长而发生变化.

Flow stress behaviors of as-cast Al-Zn-Mg-Cu high strength aluminum alloy during static restore processes were investigated by: Isothermal double-pass compression tests at temperatures of 300-400℃,strain rates of 0.01-1 s-1,strains of 33% +20% with the holding times of 0~900 s after the first pass compression.The results indicate that the deformation temperature has a dramatical effect on mechanical behaviors during static restore processes of the alloy.(1) At 300 ℃ and 330 ℃ lower temperatures,the recovery during the deformation is slow,and deformation energy stored in matrix is higher,flow stresses at the second pass deformation decreased during the recovery and recrystallization,and the stress softening phenomena is observed.Stress softening is increased with the increasing holding time;Precipitation during the holding time inhibites the stress softening.(2) At 360 ℃ and 400 ℃ higher temperatures,the recovery during deformation is rapid,and deformation energy stored in matrix is lower.Solid solubility is higher after holding,so that flow stress at the second pass deformation is increased,stress hardening phenomena is observed.Stress hardening decreased with the increasing holding time duo to the recovery and recrystallization during holding period at 360 ℃;Precipitation during holding also inhibited the stress softening.However,Stress hardening remains constant with the increasing holding time duo to the reasanenal there are no recovery and recrystallization during holding period at 400 ℃.