Austenitic cast iron is produced by taking a normal grey or ductile iron melt, controlling the carbon and silicon at lower levels and adding various alloys to produce a stable austenitic structure at ambient temperature. Nickel is the main alloying element, hence the alternative name of Ni Resist, and is the principle reason why the casting has an austenitic structure with nickel stabilising the austenite during solidification.
Because of the nickel content, austenitic cast iron is more expensive than grey or ductile cast iron but is usually cheaper than an equivalent alloyed steel, particularly if the cost of machining the casting is taken into account. It is far easier to machine than a nickel chrome steel.
At Durham Foundry we have been producing austenitic iron castings for over twenty five years. As well as austenitic iron castings, our customer base also covers grey, ductile and alloyed irons for the engineering, decorative, architectural and artistic sectors and we can supply castings from one off up to small to medium batch production using Alkali Phenolic resin bonded sands. Our workforce of highly skilled moulders can work from complex loose pattern equipment, particularly where low volumes are required, whilst our moulding line is suited for batch production.
Our long trading history, coupled with an investment programme that has enabled us to keep up with modern production methods and environmental legislation has meant that we have been involved with many projects requiring austenitic iron castings and continue to be so. All our austenitic iron castings are produced to the current ISO material specification, ISO 2892 1973, along with any further certification which a customer may require.
Our diverse customer base has also given us experience in a wide range of applications for austenitic iron castings, including pumps and valves, forges, foundries and rolling mills, automotive and aerospace, a wide range of OEM's, quarries and mines, railways and rolling stock, local authorities and artists and sculptors.
We also have long term trading relationships with local pattern makers, machine shops and surface finishers which enable us to quote for the complete supply of the finished casting. In many cases we project manage the whole process and offer expertise in Austenitic Castings & Ni Resist Cast iron. Call Durham Foundry on 0114 249 4977 to discuss your Austenitic Iron Castings & NI Resist Cast Iron project.
Austenitic irons, which can be produced with either a flake graphite or a spheroidal graphite structure, have a range of properties which far out perform a normal grey or ductile iron. These include good scaling resistance, high resistance to heat, good thermal expansion characteristics, resistance to corrosion in sea water and alkaline liquids and atmospheres, good cold toughness and resistance to erosion. Certain grades are also non magnetic. They offer numerous economic advantages compared to non-corrosive heat resistant steel because the production process control is far simpler, the melting and casting temperatures are lower, the castings don’t require heat treatment and the metal has better machining characteristics.
The large variety of characteristics are controlled using a range of alloying metals. The high nickel content increases the tensile strength and elongation at fracture without adversely affecting the yield strength or hardness. The nickel also produces an alloy with low thermal expansion which can be adjusted by controlling the nickel content. Along with nickel as the primary addition, chromium will improve corrosion resistance, strength and performance at elevated temperatures but excessive amounts can cause the formation of carbides which would give a brittle structure and problems in machining. For this reason it is controlled at much lower levels than the nickel.
Copper can be added to improve corrosion resistance and manganese improves cold toughness. Molybdenum improves high temperature performance. The ability to influence such a wide range of properties has meant that austenitic cast iron can be used in many applications such as pumps and valves operating at elevated temperatures or carrying corrosive liquids and gases, exhaust gas manifolds and turbocharger housings, switchgear housings, insulator flanges, terminals and ducts, furnace components and piston ring carriers.
As can be seen, the range of uses for austenitic cast iron is large and we are happy to advice on the correct grade for a given application. These days the spheroidal graphite grades are more important that the flake graphite ones due to their greater strength and toughness and their lower susceptibility to growth at elevated temperatures.
Please browse our website for more information about Durham Foundry and our ability to manufacture Austenitic Castings & Ni Resist Cast Iron then contact us on 0114 249 4977 or e-mail us on firstname.lastname@example.org.