Cast Iron

Cast irons are iron-carbon alloys typically containing 1,7-6,7% carbon, 1-3% silicon, and trace amounts of elements like manganese, phosphorous, and Sulphur. These alloys are cost-effective, durable, and easily cast. Depending on their chemical composition and cooling rates, cast irons can be categorized into two main groups: white cast irons and grey cast irons, distinguished by their fracture characteristics.

White cast iron is achieved through rapid or non-equilibrium cooling during casting, featuring slightly lower levels of carbon and silicon compared to grey cast irons. It exhibits a hard microstructure composed of pearlite and cementite (iron carbide), imparting exceptional hardness but also brittleness to the alloy. Due to its nil ductility, white cast iron is primarily used in wear applications and is not considered weldable. 

However, white cast iron can undergo a high-temperature annealing process, known as malleabilization, within a temperature range of 800-860°C (1475-1580°F) for 30 to 40 hours. This treatment transforms hard white cast iron into malleable iron with improved ductility by breaking down iron carbides and precipitating graphite nodules (temper graphite) in the matrix. 

Grey cast irons, on the other hand, are formulated from chemical compositions with higher levels of carbon (2,5-4%) and silicon (1-3,0%), utilizing an equilibrium cooling mode. They derive their name from their grey fracture surface, resulting from nearly all of the carbon content crystallizing into graphite. 

Seeking expert advice on choosing the right cast iron type for your project or need assistance with heat treatment techniques? Contact us today to tap into our expertise and discover how our solutions can meet your specific requirements !