Hot isostatic pressing (HIP) to achieve isotropic microstructure and retain as-built strength in additive manufacturing titanium alloy (Ti-6Al-4V)
Jake T. Benzing, Nikolas W. Hrabe, Timothy P. Quinn, Ryan M. White, Ross A. Rentz, Magnus Ahlfors
Hot isostatic pressing (HIP) treatments are used to seal internal porosity because defects exist in as-built Ti-6Al-4V parts produced by electron beam melting powder bed fusion. Standard HIP treatment of Ti-6Al-4V parts reduces internal porosity but results in decreased strength. We present a new HIP strategy with the following steps: hold above the β-transus, rapid quenching, and tempering. This new HIP treatment seals internal porosity, causes a columnar to equiaxed transition of prior-β grains, changes the α lath aspect ratio, removes microstructural heterogeneities and matches the yield and ultimate tensile strength of the as-built condition.