Strength of an ?-alloy of titanium taking into consideration its hydrogen impregnation

Abstract

Results are presented of an investigation of the influence of the conditions of conduct of an experiment on the appearance of hydrogen embrittlement of PT-7M ..cap alpha..-titanium alloy hydrogen impregnated to various concentrations. Tensile tests of notched and unnotched specimens, impact bend tests, and static three-point bend tests of specimens with a crack were made in a broad temperature range. To determine the fracture toughness, specimens with a center notch and a fatigue crack recommended for finding the critical stress intensity factors and the critical crack opening were used. Metallography was used to determine the dependence of lamellar titanium hydride formations on hydrogen content. The results of calculation of the critical crack opening made it possible to predict the character of failure of cylindrical thin-walled shells of the alloy. Maximum allowable shell thickness, beyond which brittle fracture occurs, could be established from ductile-to-brittle transition curves. The most sensitive methods for determining a tendency toward hydrogen brittleness were impact strength and fracture toughness tests.