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| The controlled heating and cooling of metals (Heat Treatment) alters their physical and mechanical properties without changing the product shape, and increase the metal strength and/or product performance. This can be achieved by hardening, tempering, annealing and stress relieving. Heat Treatment is also used to assist in the improvement of machining, formability and restoring ductility after a cold working operation. Typical temperature ranges for heat treatment at Thos C Wild are between 500°C and 1200°C.
Hardening
Hardening of metal involves heating above the critical transformation temperature and cooling rapidly, either by quenching in oil, water or air cooled, depending of the alloying composition of the metal.
Rapid cooling will cause the soft initial structure to transform to a much harder, stronger structure. Hardening will give improved mechanical properties and an increase in hardness, producing a tougher and more durable product. Hardening is then subsequently tempered, aged or stress relieved to improve toughness, hardness and dimensional stability.
Tempering
Tempering is carried out to relieve stresses and give the desired hardness, strength and toughness of a hardened metal. It is carried out after quenching or air cooling operation, and is effective in relieving stresses that have been induced by quenching. Tempering may allow the hardness to be achieved within a specified range, and can enhance mechanical property requirements. |
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Processes