Effect of Hydrogen on Mechanical Properties of Aluminum AA 6061 Alloy Hardened by Precipitation

Abstract

ABSTRACTThe present work reports on the effect of hydrogen on mechanical properties of aluminum AA 6061 hardened by precipitation. Test specimens are solution treated in an electric induction furnace at 803 K during 1 hour and then precipitation hardened during 4 hours at 423, 448 and 473 K. The heat treated specimens are subjected to a hydrogen cathodic charging process during 0, 24 and 96 hours and then tested under monotonic uniaxial tensile loading according to ASTM E8-03. Scanning electron microscopy characterization of tensile fracture surfaces reveals that hydrogen charging of precipitation hardened specimens enhances intergranular cracking by microvoid coalescence and intragranular cleavage fracture. The results show that, although hydrogen charging causes embrittlement of precipitation hardened aluminum AA 6061, the effect is a function of time; short time cathodic charging increases the ductility of the alloy.