Numerical prediction of process-dependent properties of Ti-6Al-4V in hot-forming applications with LS-DYNA

The use of high-performance materials and modern manufacturing processes has made it possible to achieve components with ever lower weights at the same load capacity. The local mechanical properties are process-dependent and result from different mechanisms in the material, such as work-hardening effects, microstructure phase-evolution and other processes affecting geometrical aspects of the microstructure. In this contribution, focus is put on the modelling of Ti-6Al-4V. The mechanical strength of this material grade significantly depends on the microstructure phase composition but also on the lath thickness of the martensitic phase. Both properties are direct results of the local temperature history for the material and, thus, have to be accounted for by a numerical material model. The recently enhanced material model *MAT_GENERALIZED_PHASE_CHANGE / *MAT_254 in LS-DYNA offers a framework to model phase changes in the microstructure with up to 24 individual phases and to predict the evolution of generalized internal variables. It will be shown how the specific features of Ti-6Al-4V mentioned above can be translated into this framework. Simple validation examples show that the new implementation predicts resulting mechanical properties in accordance with literature data. Moreover, the simulation of a hot-forming process demonstrates the benefits of the material implementation in combination with multi-physics capabilities of LS-DYNA. The evolution of the internal processes will be shown and discussed and the corresponding predicted strength distribution presented.