Effect of annealing treatment on microstructure and mechanical properties of hot isostatic pressing compacts fabricated using Ti–6Al–4V powder

Abstract

The effects of annealing temperature and annealing time on microstructure evolution and mechanical properties of Ti–6Al–4V titanium alloy prepared using powder hot isostatic pressing were investigated. The results showed that when annealing temperature was < 1173 K, the globularisation of primary α was observed, and the morphology of secondary α changed from acicular shapes to acicular and continuous lathy grains. Scanning electron microscopy fracture surface showed that the fracture mechanism changed from transcrystalline dimple type to a mixture of transcrystalline and intercrystalline dimple types with increasing annealing temperature. The tensile strength and elongation varied with the temperature in an opposite trend. However, they varied similarly with increasing annealing time. Microhardness was sensitive to the annealing time, resulting into a maximum microhardness of 396.95 HV at 1173 K for 3 h.

Keywords:

• Ti–6Al–4V
• Hot isostatic pressing
• Microstructure evolution
• Mechanical properties

Acknowledgement

The authors appreciate the Institute of Metal Research, Chinese Academy of Sciences for providing the materials.