High strain rate superplasticity at intermediate temperatures of the Al 7075 alloy severely processed by equal channel angular pressing

JOURNAL OF ALLOYS AND COMPOUNDS

卷:509

Article

Cepeda-Jimenez, C. M.¹  Garcia-Infanta, J. M.¹  Ruano, O. A.¹  Carreno, F.¹ 

[1] CSIC, CENIM, Dept Met Phys, Madrid 28040, Spain

关键词: Al-Zn-Mg-Cu alloy;    ECAP;    Superplasticity;    Deformation mechanisms;    Microstructure;   

DOI  :  10.1016/j.jallcom.2011.07.076

来源: Elsevier

【 摘 要 】

The mechanical properties of an overaged Al 7075-O alloy processed by ECAP were examined by tensile tests at intermediate-high temperatures ranging from 250 to 400 degrees C and strain rates from 10(-5) to 10(-1) s(-1). The influence of the number of ECAP passes on the ductility enhancement was evaluated. Elongation to failure, e(F), significantly increased with increasing the number of ECAP passes up to 8 at 130 degrees C. The alloy processed under these conditions exhibited a maximum value of 322% at 300 degrees C and an initial strain rate of 10(-3) s(-1). High strain rate, e(F) = 210%, at a strain rate as high as 10(-2) s(-1). The large elongations together with lower stresses and lower stress exponents than those for the start material confirm that grain boundary sliding (GBS) is the operative deformation mechanism. A loss of superplastic behaviour at temperatures above 350 degrees C is related to abnormal grain growth and a change of deformation mechanism. (C) 2011 Elsevier B.V. All rights reserved.

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