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Ni-Hard is a white cast iron, alloyed with nickel and chromium suitable for low impact, sliding abrasion for both wet and dry applications. Ni-Hard is an extremely wear resistant material, cast in forms and shapes which are ideal for use in abrasive and wear environments and applications.
- Ductile Iron
Ductile Iron Ductile iron, also known as ductile cast iron,...
- White Cast Iron
White Cast Iron A type of cast iron with lower levels of...
- Ni-Hard
Ni-Hard is a white cast iron, alloyed with nickel and...
- Ductile Iron
Ni-Hard is a white cast iron, alloyed with nickel and chromium suitable for low impact, sliding abrasion for both wet and dry applications. Ni-Hard is an extremely wear resistant material, cast in forms and shapes which are ideal for use in abrasive and wear environments and applications.
- Abrasion resistance
- Carbon content and microstructure
- Carbon %
- Resistance to fracture
- NI-HARD GRADES AND COMPOSITIONS
- Silicon
- Sulfur and phosphorus
- Special Ni-Hard 1 and 2
- Graphite
- PRODUCTION
- Melting
- Bimetallic and compound castings
- Compound castings
- Average analysis (%) of Ni-Hards used in cryogenic tests
- Finishing the castings
- TESTING
- Soundness
The abrasion resistance of a material is not a distinct property like hardness or tensile strength but depends on the system where abrasion takes place. This so-called tribological system is complex: subtle changes may result in signifi cant changes in service life or relative performance of different materials. Abrasion resistance cannot be easily...
The abrasion resistance of iron and steel correlates rea-sonably well with their carbon content and microstruc-ture. Generally, abrasion resistance will increase with carbon content, provided free graphite is absent. Figure 2 Abrasion resistance of various iron-base alloys as infl uenced by their hardness. Wear pot test with quartz 3.4 Vickers ha...
1 Martensitic (Q+T) steels and white cast irons 2 Austenitic steels and white cast irons 3 Pearlitic white cast irons Pearlitic white irons show a rather poor performance despite their high carbon content, because their weak matrix cannot support the brittle carbides because chipping may occur. The distance between the three fields shown in Figure ...
An important consideration in the selection of abrasion-resistant irons and steels is their resistance to fracture. The toughness of white irons is as dificult to quantify as is resistance to abrasion. The usual methods for measuring toughness in ductile materials–like tensile elongation or notched or unnotched impact resistance–do not apply to the...
Ni-Hard has a microstructure consisting of carbides and a martensitic-austenitic-bainitic or predominantly martensitic matrix. This is achieved by a balanced composition of carbon, nickel, chromium, silicon and final heat treatment.
Silicon is a graphitiser and should be kept at a low level in order to avoid the formation of graphite, which reduces abrasion resistance. However, enough silicon is necessary to avoid casting defects. Thus, there is a balance in silicon content necessary to optimise abrasion resistance but minimise casting defects. Also, the matrix will contain a ...
Both elements reduce the toughness of Ni-Hard and should therefore be kept to the lowest level practicable. Sulfur is also known to decrease the abrasion resistance of white irons.
The base composition of standard Ni-Hard has been modifi ed in some instances to give grades with improved properties or special- purpose grades. Wear segments for Clinker Grinder
If the silicon content is not balanced by an adequate amount of chromium for a given section, graphite will be precipitated. Uncontrolled graphite precipitates, as shown in Figure 8 in the zones between the eutectic carbides, are undesirable because they reduce abrasion resistance. In rolling mills, where a completely different wear mechanism opera...
In considering production practice, Ni-Hard should be considered as a high-strength ferrous material. Casting quality and service performance are determined by charge materials, composition and melting practice as well as moulding, internal and external soundness, and surface fi nish. These must be carefully controlled.
Ni-Hard 1 was originally designed for cupola melting, but today the use of electric melting is almost universal. Cupola melting Ni-Hard 1 or 2 will not produce high-quality cast-ings. Melting Ni-Hard 4 in a cupola is not recommended because of the excessive carbon pickup of this high-chromium alloy. Melting Ni-Hard in modern rotary furnaces with ox...
The idea of combining the high abrasion resistance of Ni-Hard with the toughness and machinability of steel or graphitic cast iron has led to the development of various techniques to produce bimetallic or compound castings.
Reinforcing Ni-Hard with cast-in steel bars or rods is simple and eficient. The diameter of the rods is adapted to the section of the casting and they are placed well removed from the working face. The reinforcement extends both longitudinally and laterally in the casting and can take the form of a lattice or spiral arrangement. Care is taken to av...
results. Since similar and higher as-cast hardness values can be reached with optimised compositions, such treatment has not achieved commercial signifi cance. This treatment may be considered for hardening complex castings where heat treatment is considered too risky.
For easy riser removal, breaker cores should be used. But care must be taken to avoid breaking into the body of the casting. Grinding is best done after heat treatment, to minimise the risk of heat checking and grinding cracks. The temperature generated during grinding must be controlled for the same reason. Comparatively soft grinding wheels are n...
The most significant property of Ni-Hard castings is their hardness — and hardness is usually the only property that is determined in practice. The determination of other properties usually asked for in steels or grey irons – like tensile or bending strength — is dificult and costly. Even the manufacture of suitable test samples from the hard and b...
Castings are usually checked for surface cracks by the dye penetrant method. Eddy current or Magna Flux can also be used but retained austenite may give wrong indications. The soundness of the castings can be determined by means of the usual ultrasonic or X-ray methods.
With careful precision and artistic creativity we have the ability to render architectural and historical castings. Using prints, sketches or even original pieces we have reproduced historical castings such as entire fence segments including decorative florets, bases, post and finials.
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Aug 3, 2023 · Various types of cast irons are produced using different heat treatment and processing techniques, including gray iron, white iron, malleable iron, ductile iron, and compacted graphite iron. Cast iron design details are produced by smelting metal and pouring it into a mold.
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Feb 14, 2024 · The first step to properly welding cast iron, cast steel, or other cast metals, is understanding the unique challenges you’ll have to overcome. For cast iron, the most common kind of cast metal you’ll be welding, your primary challenge is the carbon content of the metal.
