Exam Question

Hydrogen damage refers to the mechanical degradation of metals caused by interaction with or the presence of hydrogen. The damage mechanism fundamentally relies on the ability of nascent, atomic hydrogen (H), which is very small, to diffuse into the metal lattice. Once inside, it can cause damage through various physical and chemical processes. This is distinct from molecular hydrogen (H₂), which is stable and too large to diffuse through the metal matrix.
### (a) Hydrogen Blistering
**Mechanism:**
Hydrogen blistering is a form of mechanical damage characterized by the formation of surface blisters on the metal. The process occurs as follows: