reharden
/rɪˈhɑːrdən/Definitions
1. verb
to make hard again, especially metal, by heating and cooling it
“The blacksmith had to reharden the broken sword for it to be usable again.”
2. verb
to make something harder or more resistant to wear
“The manufacturer rehardened the metal to make it more durable.”
3. noun
the act of making something hard again
“The process of rehardening the metal took several days.”