pitting vs corroding

pitting and corroding both are nouns.

Word	Noun	Adjective	Verb	Adverb
pitting	Yes	No	No	No
corroding	Yes	No	No	No

As nouns, corroding is a hypernym of pitting; that is, corroding is a word with a broader meaning than pitting:

pitting: the formation of small pits in a surface as a consequence of corrosion
corroding: erosion by chemical action

Other hypernyms of pitting include corrosion, erosion.

pitting (noun)	corroding (noun)
the formation of small pits in a surface as a consequence of corrosion	erosion by chemical action