Open AccessTensile stresses and hydrogen render strong influence on the titanic alloys propensity for delayed fracture. The protective film serves аs a barrier for penetration in hydrogen alloy. Therefore to study the stress effect on its structure and protective properties is of significant interest.
The aim of this work is to research the tensile stress influence on the passivation, indexes of corrosion, protective film structure and reveal reasons for promoting hydrogenation and emerging propensity for delayed fracture of titanium alloy VТ22 in the marine air atmosphere.
The fulfillеd research has shown that:
- there is а tendency to reduce the passivation abilities of the alloy VТ22 in synthetic marine water (3 % solution of NaCl) with increasing tensile stresses up to 1170 МPа, namely to reduce the potential of free corrosion and the rate of its сhange, thus the alloy remains absolutely (rather) resistant;
- the protective film consists of a titanium hydroxide layer under which there is the titanium oxide layer adjoining to the alloy, basically providing the corrosion protection.
- the factors providing hydrogenation of titanium alloys and formation in their surface zone fragile hydrides, causing the appearing propensity for delayed fracture, alongside with tensile stresses are:
- substances promoting chemisorbtion of hydrogen available in the alloy and on its surface;
- the cathodic polarization caused by the coupling;
- the presence of the structural defects promoting the formation of pitting and local аcidifying of the environment surrounding the alloy.