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Wear Resistant and Ni Hard Cast Iron Castings


Cast iron, in the grade normally used for items such as bearing housings, gearboxes or machine beds, has a hardness of about 150 to 200 Brinell. With the addition of alloying elements, usually chrome, nickel or copper, the hardness can be increased to over 700 Brinell. This has opened up the use of cast iron into areas where wear resistance was a crucial requirement. Examples of these uses include mixer paddles, augurs and dies in the clay industry, liner plates for ball mills and coal chutes, wire guides for wire drawing and shotblast spares.

At the Foundry we have been producing wear resistant iron castings for over twenty five years. As well as castings for wear resistant applications, our customer base also covers 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 abrasion resistant castings and continue to be so.

All our wear resistant castings are produced to the current ISO material specification, ISO 21988 2006, along with any further certification which a customer may require. Our diverse customer base has also given us experience in a wide range of other applications for iron castings , including pumps and valves, forges, foundries and rolling mills, automotive and aerospace, a wide range of OEMs, 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 Wear Resistant & Ni Hard Cast Iron Castings.

Wear resistance can be achieved in cast iron in two basic ways. Firstly a normal grey iron can have small additions of copper, molybdenum, vanadium or chrome added. These are usually up to 1% and can increase the hardness from a base of about 150 Brinell up to 200 to 300 Brinell by promoting the formation of pearlite in the casting, particularly if the carbon and silicon levels are controlled to the lower end of the desired range. If these hardness’s are sufficient, this method has the advantage that the resultant alloy is still machineable.

The second method involves the use of chrome and nickel in much higher quantities, the chrome content being as high as 28% to create a structure that includes a high proportion of primary carbides. Although a lot of chrome iron castings are supplied in the as cast state, these alloys are heat treatable, which promotes the growth of secondary carbides, and can attain hardness’s as high as 700 Brinell. Tempering can be used to increase the toughness. This second method is, unfortunately, only machineable using special techniques and cutting processes which usually results in castings that are cast to size. Where fixings are required it is possible to cast in threaded bars or blocks of steel that can be drilled and tapped after the casting is made to give fixing and location points.

There are a number of ways of describing this highly alloyed type of iron – Chrome Iron, Wear Resistant Iron, Ni Hard or 28% Chrome being the more common ones, along with a range of national and international standards. This can cause some confusion and at Durham Foundry we are happy to advice on a suitable grade that will give the wear resistance required. One side effect of the levels of chrome and nickel used in these grades is that they can have good corrosion resistance which can lead to alternative applications. Also, given the inherently higher melting point of chrome compared to cast iron, they can be used for heat resistant castings, particularly if the carbon content is controlled to the lower end of the permissible range in some of the 28% chrome grades. These heat resistant versions have applications in castings such as fire bars and grate assemblies in stoves.





Liaoning Borui Machinery Co., Ltd. All rights reserved.
Add: No.1-4-6, Jianshe Road, Qianyang, Donggang City, Dandong, Liaoning, China 
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