Effect of hydrogen on mechanical properties and microstructure of T52YL titanium alloys

By hydrogen charging and testing of virgin samples in a hydrogen environment, the effects of hydrogen on the mechanical properties of T52YL titanium alloys at room temperature have been investigated. Embrittlement sensitivity in an H-2 environment is not susceptible. However, after hydrogen charging, the elongation decreased with increasing hydrogen content in the alloy. The hydrogen embrittlement sensitivity of the alloy increased with the increase in strain rate. Especially, the impact ductility decreased rapidly with the increase of hydrogen concentration in the alloy. The microstructure of the alloy, fracture surfaces and hydride phases have been studied. The feature of the fracture surfaces is quite different for alloys with a hydrogen content varying from 45 ppm to 2600 ppm. The ductile dimples constitute the main characteristic on the fracture surfaces of the received materials (less than 80 ppm H), whereas cleavage is shown on the hydrogen charged specimens. The nature of hydrogen embrittlement of the T52YL Ti alloy, which seems to belong to the first type of (hydride) H embrittlement, is also discussed.