Influence of hydrogen content on room temperature compressive properties of Ti-6Al-4V alloy at high strain rate

Electromagnetic forming tests were done at room temperature to reveal the influence of hydrogen content on the compressive properties of Ti-6Al-4V alloy at high strain rate. Microstructure was observed to reveal the mechanism of hydrogen-enhanced compressive properties. The experimental results indicate that hydrogen has favorable effects on the compressive properties of Ti-6Al-4V alloy at high strain rate. Compression of Ti-6Al-4V alloy first increases up to a maximum and then decreases with the increase of hydrogen content at the same discharge energy under EMF tests. The compression increases by 47.0% when 0.2% (mass fraction) hydrogen is introduced into Ti-6Al-4V alloy. The optimal hydrogen content for cold formation of Ti–6Al–4V alloy under EMF was determined. The reasons for the hydrogen-induced compressive properties were discussed.

Influence of Hydrogen on the Microstructures and Superplasticity of a Ti_3Al-Nb Alloy

The effect of hydrogen on the microstructures and superplasticity of a Ti3Al-Nb alloy was studied. The results showed that hydrogenation made the volume fraction of B2 phase increase and facilitated the dynamic recrystallization of the lath-like phase. The addition of hydrogen. reduced the flow stresses and made the maximum m value move to a lower temperature during the superplastic deformation. The superplastic deformation temperature of the alloy can be lowered by about 60 degreesC.

Recent Advances in the Hot Working of Titanium Alloys

In this paper, recent advances in titanium alloy processing are reviewed. The casting, superplastic forming, friction stir welding and thermohydrogen processing of titanium alloys are developed. The great cost saving results from using casting comparing with the conventional machining for rings. The superplastic forming of titanium alloys is a feasible manufacturing technology for civil and military aircraft. The friction stir welding leds to the production of fully-formed, high quality friction stirwelds. In thermohydrogen processing, the high diffusivity of hydrogen in titanium is firstly used to add hydrogen to titanium alloys by controlled diffusion from a hydrogen environment , after thermohydrogen processing, to remove it by a controlled vacuum anneal so as to improve processing and mechanical properties.

Microstructure and properties of hydrogenated TB8 alloy

Thermohydrogen processing can enhance workability, decrease flow stress and deforming tempera- ture of titanium alloys. In this study, thermohydrogen processing was carried out for metastable β-type TB8 alloy. The microstructures of hydrogenated TB8 alloy were investigated based on scanning electron microscopy （SEM）, transmission electronic microscopy （TEM） as well as X-ray diffraction （XRD） analysis. The results reveal that 6 hydride phase forms in the hydrogenated TB8 alloy, but the amount of β phase increases with hydrogen content increasing. Single β phase appears when the hydrogen content reaches 0.7 wt%. The alloying elements redistrib- ute in the hydrogenated TB8 alloy, and hydrogen leads to the reduction of the alloying elements in β phase. The room-temperature compression tests were performed on a MTS809 machine. It is found that the room-temperature yield strength of hydrogenated TB8 alloy decreases. And minimum yield strength is obtained at a hydrogen content of 0.5 wt%. The ductility does not decrease within 0.7 wt% hydrogen content. These results provide theoretical basis for improving the formability and promoting the applica- tions of TB8 alloy.