High temperature deformation of solution treated 7010 Al-alloy

The deformation behavior of 7010 Al-alloy at elevated temperature was investigated.The specimens were solution treated at 723 K for 2 h and then water quenched to obtain the supersaturated solid solution (SSS). Tension tests of the SSS specimens were then conducted at temperatures of 623, 673, and 723 K at various strain rates in the range 5 ˣ 10-5 to 2 ˣ 10 - 2 s -1. Stress dependence of the strain rate revealed a stress exponent, n of ~ 8 throughout the ranges of temperatures and strain rates used. This stress exponent is higher than what is normally observed in Al–Zn alloys under similar experimental conditions. This high value of the stress exponent implies the presence of the threshold stress. This behavior resulted from a dislocation interaction with second phase particles due to precipitation at testing temperatures. The values of the threshold stress were observed to decrease exponentially with temperature. The presence of the threshold stress resulted in high apparent activation energy (~180 kJ/mol). The true activation energy was obtained by incorporating the threshold stress in the analysis. The normalized constitutive equation was then developed for the alloy under the present experimental conditions