How can you temper steel into a spring?

To temper steel into a spring, first heat the steel to a specific temperature, typically between 150°C to 300°C (300°F to 570°F), after it has been hardened through quenching. This process relieves internal stresses and enhances ductility while retaining some hardness. The steel is then cooled slowly in air, which helps achieve the desired balance of strength and flexibility necessary for spring applications. Finally, the spring can be shaped and finished to meet specific design requirements.