Читать книгу Root Cause Failure Analysis - Trinath Sahoo - Страница 110

Failure is time‐dependent and occurs at low rates of strain as the load‐bearing cross section is reduced during slow crack growth in the embrittled region. Susceptibility for embrittlement is higher in alloys with higher yield strengths, i.e. those that are cold‐worked, age‐hardened or in their martensitic form. The sites at which hydrogen is trapped include the original austenite grain boundaries and the interfaces between the matrix and non‐metallic inclusions, for example, manganese sulfides. These then result in both intergranular cracking (with separation at the prior austenite boundaries) and transgranular cracking (flaking or quasi‐cleavage) which is associated with the inclusions. Hydrogen can assist in the propagation of corrosion fatigue cracks and can also cause sulfide stress corrosion cracking in ferritic and martensitic steels, including the stainless grades.