Al-Mg alloys have seen an increasing adoption in the automotive industry essentially due to their lightweight features. Warming forming processes have been popularly applied to overcome the drawback of low formability exhibited by this class of materials at room temperatures. A new combined isotropic kinematic hardening model was recently developed by the authors for assessing steel materials at elevated temperatures. The new model integrates temperature effects on the yield surfaces through the concept of a shrinking/expanding bounding surface, and on the Bauschinger effect using an exponential growth function of plastic internal variables (PIVs). Transient hardening behaviour is modelled by incorporating a second non-linear kinematic hardening variable using an exponential decay function of the PIVs. In this paper, the new model is further developed and applied to simulate the warming forming process, with the non-quadratic anisotropic yield function, Barlat Yld2000, adopted to describe the plastic anisotropy. The accuracy of the proposed finite element model is assessed by comparing the numerical predictions with the experimental data of the benchmark springback problem in NUMISHEET2016.