Effect of Hot-Isostatic-Pressing Parameters on the Microstructure and Properties of Powder Ti-6Al-4V Hot-Isostatically-Pressed Samples

Ti-6Al-4V powders have been hot-isostatically-pressed (“HIPped”) using a range of hot-isostatic-pressing (“HIPping”) conditions, and the effects on microstructure and mechanical properties have been assessed. The properties were measured on test samples machined from HIPped powder billets and on samples that contained the as-HIPped surface. The fatigue limit of samples that contained the as-HIPped surface was improved by using a new HIPping procedure. The machined samples that had been HIPped at 1203 K (930 °C) exhibited a better balance of properties than those HIPped at 1153 K (880 °C) or 1293 K (1020 °C). The fine microstructure, formed from the martensitic structure of the atomized powder, coarsens with the increase of temperature or time during HIPping. These changes have been correlated with the corresponding changes in properties and with the fracture surfaces. The significance of these observations, especially the fatigue properties of samples that contain the as-HIPped surface, is discussed in terms of the properties of net-shape HIPped components.