Metal Grade Guide

Iron GradeTypical ApplicationDescription
MALLEABLE IRONUsed for small castings requiring good tensile strength and the ability to flex without breaking (ductility). Electrical fittings, hand tools, pipe fittings, washers, brackets, fence fittings, power line hardware, farm equipment,mining hardware, machine parts.Malleable Iron is the oldest member of the family of nodular irons. Like all nodular irons, Malleable Iron exhibits good ductility. Incorrectly considered by some to be an "old" or "dead" material, Malleable Iron still has a legitimate place in the design engineer's toolbag. Malleable is the iron of choice for small castings or castings with thin cross sections (less than .25"). Other nodular irons tend to be difficult to produce in these applications. Malleable Iron is also preferred for castings seeing duty in low temperature environments since it retains its ductility better than other nodular irons at low temperatures. Bowmanville Foundry produces 3 grades of Malleable Iron exhibiting varying degrees of strength and ductility. See Technical.
GRAY IRONUsed for housings where tensile strength is non critical. Engine blocks, pump housings, valve bodies, electrical boxes, decorative castings. Gray Iron was the original "cast iron". It is relatively easy and inexpensive to make. Compared to the more modern engineered irons Gray Iron has a lower tensile strength and lower ductility. In other words it will fail more easily, and its mode of failure will be sudden fracture (it will not bend). Bowmanville Foundry produces 3 grades of Gray Iron, each exhibiting varying degrees of machinability and strength. See Technical.
DUCTILE IRONUsed for medium to large castings requiring high tensile strength and the ability to flex without breaking (ductility). Brake rotors, machine parts, power line hardware, construction components, farm machinery, railroad components.Ductile Iron is part of a family of irons known as "nodular irons". Developed relatively recently (in the mid-twentieth century... yes this is a very old business) Ductile Iron is where both high strength and ductility are required. This material is more than twice as strong as Gray Iron, is equally machinable, yet does not fracture when it fails, it stretches or bends. Bowmanville Foundry produces 3 grades of Ductile Iron exhibiting varying degrees of strength and ductility. See Technical.
AUSTEMPERED DUCTILE IRONUsed for castings requiring very high strength and/or wear resistance. Also used where lightweight is desired. Used anywhere as a lightweight substitute for ductile iron, cast steel, or forged steel. Shafts, gears, conveyor parts, driveline components. Austempered Ductile Iron (ADI) is the newest member of the family of nodular irons. Although somewhat more expensive to produce, ADI's mechanical properties are nothing short of amazing. Four times stronger than Gray Iron and twice as strong as regular Ductile Iron, the material still retains excellent ductility. An added bonus is that the material is very hard giving it excellent wear resistance. The material can be used to design high strength castings much lighter than previously thought possible. ADI's strength to weight ratio and fatigue properties exceed those of aluminum. ADI is a legitimate substitute in many applications for more expensive steel castings and even forgings. Bowmanville Foundry produces 5 grades of ADI exhibiting varying degrees of strength and ductility. See Technical.