How to eliminate the hazards of hydrogen embrittlement in titanium and titanium alloys?

- Jan 29, 2018-


In titanium and titanium alloys, hydrogen is soluble in the β-phase and the α-phase, and may also exist in the form of γ-phase (hydride). Hydrogen reduces the a + β / β transformation point of titanium, which is a gap-type β-stabilizing element. Hydrogen-based hydrogen embrittlement can be prevented when the hydrogen content in titanium and titanium alloys is less than 0.020%. However, stress-induced hydride hydrogen embrittlement and reversible hydrogen embrittlement in titanium and titanium alloys are hard to avoid. Hydrogen on titanium and titanium alloy performance mainly as hydrogen embrittlement.

    To reduce the hydrogen embrittlement of titanium and titanium alloys, the main measure is to reduce the hydrogen content. Practice has proved that strict control of raw materials: the use of vacuum melting, the use of neutral or oxidizing atmosphere in the process or the use of coating; heat treatment to avoid reducing atmosphere; under inert atmosphere or under vacuum protection of welding, alkali pickling try to avoid hydrogen And so on are valid. In addition, aluminum and tin can increase the solubility of hydrogen in a titanium; β stabilizing element can increase the solubility of hydrogen in titanium and titanium alloys by increasing the amount of β phase, and reduce the effect of titanium and titanium alloy on hydride and Hydride-induced hydrogen embrittlement susceptibility to hydrogen embrittlement. However, oxygen in titanium alloys promotes hydrogen embrittlement.

    Hydrogen hydrogen to form titanium hydride caused corrosion damage in the following situations: (1) If the hydrogen dispersion is slower, mainly in the hydrides will gather in the titanium surface, the appearance of hydride brittle off and then lead to accelerated corrosion ; (2) Hydrogen disperses in the orientation of stress field to form hydride under the action of stress. Because the internal microcracks disperse through the stress and form hydrogen-induced cracking: (3) Hydrogen embrittlement of the material is damaged.