Processing, microstructure, properties and fracture behaviour of Ti–6Al–4V manufactured from pre-alloyed powder

Abstract

This study investigates the consolidation of pre-alloyed Ti–6Al–4V powder through thermomechanical processing that involves cold isostatic pressing, sintering, hot pressing and extrusion. The microstructural evolution, oxygen pick-up and tensile properties attained after each major consolidation step reveal that there was a significant oxygen pick-up during de-binding/sintering, hot pressing had improved strength/ductility by eliminating porosity and extrusion resulted in a relatively fine lamellar structure. Overall, as-extruded material had an oxygen content of 0.22 wt-%, impact toughness of 21 J, yield strength of 971 MPa, ultimate strength of 1124 MPa and ductility of 9–11% which is comparable to corresponding values reported in the literature. An investigation of fracture surfaces along with crack propagation behaviour highlights that ductile fracture was the predominant mode of failure.

KEYWORDS:

• Titanium alloy
• powder metallurgy
• pre-alloyed powder
• cold isostatic pressing
• thermomechanical processing
• microstructure
• tensile properties
• impact toughness

Acknowledgements

The authors would like to express heartfelt gratitude to Bill Owers, Fei Yang and other team members for their continuous support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Ministry of Business, Innovation, and Employment, New Zealand under Grant UOWX1402