Iron, in its pure state, is silvery, shining and soft. Electron spin in Iron is unidirectional which means it can easily combine with alloying elements. This metal is also polymorphic. The crystal structure of iron can change into various forms by modifying or altering its carbon content and temperature. The properties of iron are an important factor leading to its significance among engineers, technicians and metallurgists. We, at VR Foundries, clearly understand what your iron component requires in terms of operating temperature and alloys for optimized function in its future settings. This blog deals with the common heat treatment for specific cast-iron types.

High-alloy (example high nickel-chromium, high chromium) white irons can be subjected to heat treatment. For example, nickel-chromium white-iron castings are subjected to a stress-relief heat treatment due to adequately produced, they exhibit an as-cast martensitic matrix form. Tempering is carried out between the temperature range of 205°C (400°F) and 260°C (450°F) for minimum 4 hours. This causes the tempering of the martensite, relieving all or a part of the transformation stresses, and thereby enhancing the impact toughness and strength by about 50-80%.

In the case of malleable cast iron, it can be subjected to heat treatment to a similar microstructure like ductile cast irons. Generally, heat treatment methods applied to grey cast iron types are stress relief due to its non-uniform cooling of iron castings, and to increase machinability annealing is performed. Subcritical heating applies to both. Stress relief is performed between a temperature range of 550-650°C (1020-1200°F) without considerably minimizing hardness levels and strength.

Ductile cast iron’s heat treatments include annealing and stress relief and heat treatments applied for steels include austempering, normalize and temper (for higher wear resistance and strength) and quench and temper (for the greatest strength).

We should understand that the heat treatment of cast iron merits special attention. The team responsible for heat treatment should know the different types of alloys to make sure they uniformly attain the needed metallurgical and mechanical characteristics. For all your casting needs and clarifications, simply give our expert team a shout.