Improved creep behaviour for a high strength Al-Li alloy in creep age forming: Experimental studies and constitutive modelling

The creep deformation of 3rd generation 2xxx Al-Li alloys in age forming (CAF) is unsatisfactorily low due to its high strength and required ageing temperature, especially for the commonly used T8 temper. Promoting such process will significantly reduce springback CAF, making easier compensation tool design. In this study, two possible routes inducing increased were explored, one by employing applied stress introduce small plastic strain loading stage; other conducting pre-deformation prior creep-ageing. behaviour with without was investigated through creep-ageing tests under stresses ranging from 300 430 MPa at temperature 143°C. Due decrease threshold introduced stage and/or pre-stretching, a faster increase observed both methods when surpassed 400 MPa. promotion former higher than latter above 415 A mechanism-based constitutive model proposed, additional work hardening equations describe relationship between dislocation density induced microstructural evolution reflect nonlinear methods. adequacy proposed unified demonstrated good agreement experimental data utilising adaptability multiaxial case verified using four-point bending CAF same alloy.