Effect of hot rolling temperature and thermal cycling on creep and damage behavior of powder metallurgy processed Al-SiC particulate composite

Tensile creep behavior of Al-5SiC(p) composite, powder metallurgy processed and hot-rolled at either 400 degrees C (400-HRC) or 600 degrees C (600-HRC), has been examined. Creep-tests have been carried out at temperature and stress ranges of 325-400 degrees C and 9-21 MPa, respectively. The creep behavior has been examined by analyzing steady-state creep rate, time to rupture, Larson-Miller parameter (LMP), strain fractions in primary, secondary and tertiary stages, with assessment of damage and dimple size. The creep resistance of 400-HRC with higher dislocation density is found as greater than that of 600-HRC, whereas apparent stress exponents and activation energies exceed that for dislocation climb. The results suggest possibility of life prediction using Monkman-Grant relationship and LMP variation with stress. Thermal cycling between 500 degrees C and 0 degrees C is more effective in improving creep resistance at lower temperatures, and is more beneficial for 400-HRC than for 600-HRC, confirming positive role of strain-hardening. (C) 2012 Elsevier B.V. All rights reserved.