A metallurgical marvel
Chrome brings amazing properties to the metals with which it is alloyed. Add it to carbon steel in sufficient quantities and the steel miraculously becomes “stainless” – in other words, corrosion resistant, mechanically strong, heat resistant, hard wearing, shiny and glamorous. Stainless steel, which accounts for some 66% of the use of chrome today, is found everywhere in modern life, from nuclear reactors to exhaust pipes, architecture, kitchenware and a host of other applications.
The corrosion resistance and shiny appearance of stainless steel come from an extremely thin, continuous chromium-oxide film which spontaneously forms on the surface of the steel, in the presence of air. This film renders the surface inert to chemical reaction, thus protecting steel from corrosive attack. Should the surface be damaged or scratched, this “passive” layer instantly re-forms. Thanks to chrome, stainless steel literally self-heals. In fact, chrome is the one and only magic ingredient making stainless steel “stainless”, whatever the grade.
Speciality steels produced for applications such as tools, injection moulds, camshafts, dies, bearings and mill rollers also derive the high mechanical strength, hardness and heat-resistance required from their chrome content.
Certain exceptionally demanding applications require an alloy known as chrome metal, which, is almost pure chrome (99%). Chrome metal provides the solidity and resistance to wear and high temperatures required for critical applications in the aircraft, gas, petrochemical and nuclear sectors.
Chrome is also used in alloyed cast irons, to bestow hardness and resistance to abrasion and impact. These alloys are used for applications such as pumps, valves, pipes, rolls and wear plates.