Mechanical Properties of an Al-5.4%Mg-0.5%Mn-0.1%Zr Alloy Subjected to ECAP and Rolling

Superplasticity and microstructural evolution of a commercial Al-5.4%Mg-0.5% Mn-0.1%Zr alloy subjected to severe plastic deformation through equal-channel angular pressing (ECAP) and subsequent rolling was studied in tension at strain rates ranging from 1.4x10(-4) to 5.6X10(-2) s(-1) in the temperature interval 400-550 degrees C. The alloy had an unrecrystallized microstructure with an average crystallite size less than 5 mu m. The alloy exhibited the yield strength of similar to 370 MPa, ultimate strength of similar to 450 MPa and elongation-to-failure of similar to 15% at ambient temperature. In spite of small crystallite size the alloy shows moderate superplastic properties. The highest elongation-to-failures of similar to 450% appeared at a temperature of similar to 500 degrees C and an initial strain rate of similar to 1.4x10(-3) s(-1), where the strain rate sensitivity coefficient, m, is of about 0.57. The relationship between superplastic ductilities and microstructure is discussed.