Question

3. When a heated metal is cooled it​

Answer 1

Most matter expands when heated and contracts when cooled, a principle called thermal expansion.

Answer 2

Answer:

During hardening, the metal is heated at a high temperature and this temperature is maintained until a proportion of carbon has been dissolved. Next the metal is quenched, which involves rapidly cooling it in oil or water. Hardening will produce an alloy which has high strength and wear resistance