I don't know from experience if there is a difference to US English, but the part I have put in bold is what made me say on the other thread that "the OED definitions for "bruise" that are not about human injuries (about fruit, wood, metal etc.) are all related to pounding and crushing, not scratching."
This is the verb we are talking about, and the Merriam-Webster entries for the verb relating to damage to metal also say:
" : batter, dent
That is also not scratching.
I see that M-W has an entry for the noun that links to "abrasion/scratch", but unfortunately that does not say anything about whether damage to metal is meant.
Another point is that there is a difference between schrammen and zerschrammen. Presumably the latter is more thorough? (Duden zer- "drückt in Bildungen mit Substantiven und einer Endung oder mit Verben aus, dass eine Sache durch etwas, mithilfe von etwas aufgelöst, beschädigt, zerstört wird")
When I looked up bruising to metal, I also found:
A raised area in the steel caused by an object going between the work rolls and bruising them.
(Obviously that is another, more specialist meaning - I guess probably not zerschrammen?)