Heat Treatment

The optimal combination of spring’s properties such as hardness, strength and toughness can be achieved throughout the hardening and tempering procedure (for steels in the carbon range 0.3% to 0.6%). This treatment consists of heating the spring to the hardening temperature ranges between 800C° and 900C°, depending on the particular steel analysis involved, holding for sufficient time and then rapidly cooling in oil bath (quenching). The resultant temperature changes induce physical transformation of the steel, resulting in mechanical property changes. Following quenching, spring is in its hardest but brittle condition and therefore requires a further thermal treatment (tempering), to achieve the optimal properties. This consists of re-heating the spring to a lower temperature, between 400C° and 700C° and holding for a specific time.