What is the difference between cast iron and malleable iron?
A. There are many types of cast iron. Black ironmongery is available generally in grey, (cast), iron, SG, (Spheroidal Graphite), and malleable iron. Grey iron, although relatively easy and cheap to cast, is extremely brittle, in thin sections especially, and cannot be rivetted, hammered or assembled with any ease. SG iron, although more durable than grey iron is difficult to cast into thin sections and this precludes its use in many of our products. In addition it does not possess the inherent toughness of malleable iron which is vital in the everyday use of our door and window furniture. Malleable Iron is an iron which, after casting, is subjected to a heat treatment process known as annealing. In this process castings are heated to around 1000C for up to 100 hours whilst in contact with haematite ore. The ore acts as an oxidising agent which removes carbon from the casting. It is the presence of carbon in cast iron which causes its brittleness and removing some makes the casting stro
