The influence of temporary hydrogenation on ECAP formability and low cycle fatigue life of CP titanium

It is generally believed that thermo-hydrogen processing has a beneficial effect on tensile ductility and fatigue properties of titanium. This study was concerned with investigating whether this also applies to titanium of commercial purity (CP) with an ultrafine-grained structure obtained by equal-channel angular pressing (ECAP). It was shown that despite the possibility to manipulate the microstructure of titanium the thermo-hydrogen processing offers, temporary hydrogenation was not able to improve ductility and low cycle fatigue life of CP titanium over the levels achievable by straight ECAP.

Research highlights▶ Temporary alloying with hydrogen helps modifying the microstructure of CP titanium and also results in tensile behaviour similar to that of coarse-grained Ti—almost without compromising strength. ▶ The microstructures obtained by combination of hydrogenation with ECAP have been studied. ▶ Temporary hydrogenation is not able to improve ductility and low-cycle fatigue life of CP titanium over the levels achievable by straight ECAP where the improvement is significant. ▶ A generally believed idea that thermo-hydrogen processing has a beneficial effect on tensile ductility and fatigue properties of titanium is shown not to be applicable for CP Ti.