The 7075 Al alloy was processed by accumulative roll bonding (ARB) at 350 ℃ using 2:1, 3:1 and 4:1 thickness reductions per pass (Rp) up to 8, 6 and 3 passes, respectively. Microstructural examinations of the ...The 7075 Al alloy was processed by accumulative roll bonding (ARB) at 350 ℃ using 2:1, 3:1 and 4:1 thickness reductions per pass (Rp) up to 8, 6 and 3 passes, respectively. Microstructural examinations of the processed samples revealed that ARB leads to a microstructure composed of equiaxed crystallites with a mean size generally lower than 500 nm. It was found that, due to both the stored energy through- out the processing and the particle pinning effect, the alloy is affected by discontinuous recrystallisation during the inter-pass heating stages, the precise microstructural evolution being dependent on Rp. Me- chanical testing of the ARBed samples revealed that the main active deformation mechanism in the ARBed samples in the temperature range from 250 to 350 ℃ at intermediate and high strain rates is grain bound- ary sliding, the superplastic properties being determined by both the microstructure after ARB and its thermal stability.展开更多
基金support from the CICYT (Projects Nos. MAT200914452 and MAT2012-38962)
文摘The 7075 Al alloy was processed by accumulative roll bonding (ARB) at 350 ℃ using 2:1, 3:1 and 4:1 thickness reductions per pass (Rp) up to 8, 6 and 3 passes, respectively. Microstructural examinations of the processed samples revealed that ARB leads to a microstructure composed of equiaxed crystallites with a mean size generally lower than 500 nm. It was found that, due to both the stored energy through- out the processing and the particle pinning effect, the alloy is affected by discontinuous recrystallisation during the inter-pass heating stages, the precise microstructural evolution being dependent on Rp. Me- chanical testing of the ARBed samples revealed that the main active deformation mechanism in the ARBed samples in the temperature range from 250 to 350 ℃ at intermediate and high strain rates is grain bound- ary sliding, the superplastic properties being determined by both the microstructure after ARB and its thermal stability.