Effect of Cryogenic Treatment on Residual Stress and Dimensional Stability of 2A14 Aluminium Alloy after Solid Solution and Aging
2A14 aluminum alloy was treated by annealing of(380±5)℃×120 min,solid solution of 498℃×2 h,aging of 160℃×6 h,cryogenic under different temperatures(-70,-90,-110,-130℃)for 6 h and aging of 160℃×3 h in sequence.The effect of cryogenic treatment on residual stress,phase composition,microstructure,dimensional stability and mechanical properties of the samples was investigated.The results show that the residual stress on the longitudinal section at center of the samples after different heat treatments was in the form of internal tension and external pressure.The release and stress distribution homogenization effects of cryogenic treatment increased first and then decreased with the decrease of temperature.The stress release and homogenization effects by cryogenic treatment at-90℃ were the best.The cryogenic at-130—-90℃ could refine the grains,increase the number of precipitates,reduce the size of precipitates and the dislocation density,and increase the dispersion of precipitates and dislocations.Cryogenic treatment at-130—-70℃ could improve dimensional stability,tensile strength and yield strength of 2A14 aluminium alloy,but reduced the percentage elongation after fracture.
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