Cast iron

Grey cast iron is named after its grey fractured surface, which occurs because the graphitic flakes deflect a passing crack and initiate countless new cracks as the material breaks.

Iron (Fe) accounts for more than 95% of the alloy material, while the main alloying elements are carbon (C) and silicon (Si). The amount of carbon in cast irons is 2.1-4%wt. Cast irons contain appreciable amounts of silicon, normally 1-3%wt, and consequently these alloys should be considered ternary Fe-C-Si alloys. Despite this, the principles of cast iron solidification are understood from the binary iron-carbon phase diagram, where the eutectic point lies at 1154 degrees Centigrade and 4.3% carbon. Since cast iron has nearly this composition, its melting temperature of 1150 to 1200 degrees Centigrade is about 300 degrees Centigrade lower than the melting point of pure iron.

Cast iron tends to be brittle, except for the malleable cast irons. With its low melting point, good fluidity, castability, excellent machinability and wear resistance, cast irons have become an engineering material with a wide range of applications, including pipes, decorative, machine and car parts. Also used where vibration damping is important.

SG/Ductile iron

An abbreviation for Spheroidal Graphite (SG) Cast Iron. As the name implies, graphite is present in spheroidal form instead of flakes and compared with Grey Cast Iron it has higher mechanical strength, ductility and increased shock resistance. Many different grades are available with differing tensile properties and hardness.

Brass & Gunmetal

These are alloys of copper and zinc and are used for applications where water or pressure tightness is required with resistance to corrosion. E.g. water and gas fittings, vales, marine castings, light duty bearings and decorative castings.

Aluminium

Aluminium can be alloyed with magnesium, silicon, copper and zinc to give a wide variety of applications where a low weight combined with strength or ductility or impact resistance or corrosion resistance if required. marine components, housings, automotive parts and cryogenic volutes and impellers.

Bronze

Alloys of copper and tin. This material is commonly used for heavy duty bearings and applications where its hardness, wear resistance and corrosion resistance are required. Also used extensively for artistic castings.

Aluminium bronze

Copper, tin, nickel and aluminium make up this alloy. Its high tensile strength, hardness, resistance to wear and corrosion makes this material ideal for very heavy duty bearings, valves and also for very low temperature use such as cryogenic pump couplings.

Lead

This very heavy, dense, soft and malleable metal is primarily used for marine keels, ballast weights and radiation shielding. It can be alloyed with antimony to improve hardness and reduce the tendency of bending under its own weight.