What are the two main types of environmental cracking?

What are the two main types of environmental cracking?

• A. Hydrogen-induced cracking and Caustic embrittlement
• B. Pitting and intergranular corrosion
• C. Caustic stress corrosion cracking and Caustic embrittlement
• D. Stress corrosion cracking and hydrogen embrittlement

Answer: (C)

Environmental cracking in caustic (alkaline) service occurs mainly through two distinct mechanisms. One is caustic stress corrosion cracking, where a tensile stress and highly caustic solution work together to drive crack initiation and propagation in susceptible materials. The other is caustic embrittlement, which is a ductility loss caused by exposure to caustic media; this embrittlement makes the material more prone to cracking or sudden fracture under service stresses, even if the applied stress isn’t extremely high. Why these fit best: they directly describe cracking behaviors that arise specifically from caustic environments, distinguishing between crack growth under stress (CSSC) and a general loss of ductility due to the caustic environment (caustic embrittlement). The other options mix different corrosion phenomena (pitting, intergranular corrosion) or pair mechanisms that are not both characteristic of caustic environments (for example, hydrogen-related cracking is a separate category, and combining it with caustic embrittlement isn’t the focused caustic-cracking idea).

Environmental cracking in caustic (alkaline) service occurs mainly through two distinct mechanisms. One is caustic stress corrosion cracking, where a tensile stress and highly caustic solution work together to drive crack initiation and propagation in susceptible materials. The other is caustic embrittlement, which is a ductility loss caused by exposure to caustic media; this embrittlement makes the material more prone to cracking or sudden fracture under service stresses, even if the applied stress isn’t extremely high.

Why these fit best: they directly describe cracking behaviors that arise specifically from caustic environments, distinguishing between crack growth under stress (CSSC) and a general loss of ductility due to the caustic environment (caustic embrittlement). The other options mix different corrosion phenomena (pitting, intergranular corrosion) or pair mechanisms that are not both characteristic of caustic environments (for example, hydrogen-related cracking is a separate category, and combining it with caustic embrittlement isn’t the focused caustic-cracking idea).