Development of damage maps for Ti-6Al-4V processing

Primary processing of titanium alloys involves several forging, cooling and re-heating stages of the billet, during which time the microstructure evolves along with the process conditions. Occasionally process conditions, i.e., temperature, strain, strain rate and stress state, develop across the section of the billet that can lead to surface and/or internal cracking. Optimization of process routes can minimize the risk of such occurrences and is an important part of cost reduction, especially for widely used aerospace alloys like Ti-6Al-4V. A methodology for identifying safe and unsafe process regimes utilizing DEFORM 2D and 3D finite element analysis (FEA) codes in conjunction with the Cockroft-Latham (CL) ductile fracture criteria will be presented. In addition, the effect of starting microstructure on workability limits, and experimental validation of FEA predictions will also be discussed.