Hot isostatic pressing (HIP) to achieve isotropic microstructure and retain as-built strength in an additive manufacturing titanium alloy (Ti-6Al-4V)

Jake Benzing; Nik Hrabe; Timothy Quinn; Ryan White; Ross Rentz; Magnus Ahlfors

doi:10.1016/j.matlet.2019.126690

Hot isostatic pressing (HIP) to achieve isotropic microstructure and retain as-built strength in an additive manufacturing titanium alloy (Ti-6Al-4V)

Mater Lett. 2019:257:10.1016/j.matlet.2019.126690. doi: 10.1016/j.matlet.2019.126690.

Authors

Jake Benzing¹, Nik Hrabe¹, Timothy Quinn¹, Ryan White¹, Ross Rentz¹, Magnus Ahlfors²

Affiliations

¹ National Institute of Standards and Technology, Applied Chemicals and Materials Division, 325 Broadway, MS-647, Boulder, CO 80305, USA.
² Quintus Technologies, 8270 Green Meadows Dr. N, Lewis Center, OH 43035, USA.

Abstract

Hot isostatic pressing (HIP) treatments are traditionally 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 results in decreased strength due to coarsening of the microstructure. 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 in morphology 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.

Keywords: Additive manufacturing; Hot isostatic pressing; Microstructure; Recrystallization; Ti-6Al-4V.

Grants and funding

9999-NIST/ImNIST/Intramural NIST DOC/United States