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Materials and grades

Six alloy families, poured to IS, ASTM, EN or your own specification and chosen for the duty rather than the catalogue.

The right grade is decided by what the part meets in service: impact, sliding abrasion, heat or all three at once. Our metallurgists confirm the grade with every quotation. Every heat is analysed before the casting ships.

I know my grade: can you make it?

Type a designation from your drawing or specification.

I know my application: which grade?

Four questions about where the part works.

1. Does the part work in hot gas or hot clinker, above about 700 °C?

2. What is its main job?

3. How hard is it struck?

4. Can tramp metal or uncrushable pieces reach it?

A good starting point

Cr-Mo and martensitic steels

See the grade

A starting point, not a specification. A metallurgist confirms the grade with every quotation.

Hardness at a glance

Typical Brinell hardness as supplied. The hatched band shows how far manganese steel hardens at the face in service.

Manganese steel190–240 HB, over 500 in service

Cr-Mo steel300–550 HB

High-chromium iron550–700 HB

Ni-Hard500–650 HB

Carbon or low-alloy steel150–300 HB

Heat-resistant steels: typical service limit

In oxidising atmospheres. Thermal cycling, load and sulphur lower the practical limit.

HHabout 1,100 °C

HKabout 1,150 °C

The six families

Austenitic manganese steel

Hadfield steel. Standard 12–14% Mn, with 18% and 22% Mn types for heavier work hardening.

ASTM A128IS 276EN 10349

Chemistry: About 1.0–1.4% carbon with 11–14% manganese; higher-manganese types and chromium or molybdenum additions for harder, more abrasive rock.
Hardness: About 190–240 HB as water-quenched. The working face hardens to over 500 HB under repeated impact while the core stays tough.
Heat treatment: Solution-treated above 1,000 °C and quenched in water. Our castings leave the furnace and enter the quench in about 45 seconds.
Strength: Very high toughness. The part gets harder where it is struck, so it resists gouging without becoming brittle.
Limits: Needs impact to harden: under sliding abrasion with little impact it wears quickly. It is non-magnetic, so surfaces are checked with dye penetrant, not magnetic particles.

Parts we make in it

Hammers and beaters Blow bars Impact plates Grinding paths Grizzly bars Jaw and side plates Concaves and mantles Bowl liners Track shoes Apron pans and sprockets Feed chute liners

Cr-Mo and martensitic steels

Pearlitic and martensitic low-alloy wear steels.

IS 4896Customer specification

Chemistry: Medium- and high-carbon steels alloyed with chromium and molybdenum, with nickel added for hardenability in heavy sections.
Hardness: Typically 300–400 HB for pearlitic mill-liner grades and 450–550 HB or more for martensitic grades, set by heat treatment.
Heat treatment: Normalised or hardened in air or oil, then tempered to the required balance of hardness and toughness.
Strength: The middle ground: harder than manganese steel without needing impact, yet much tougher than white iron.
Limits: Outworn by white iron under pure abrasion and less forgiving than manganese steel when tramp metal enters.

Parts we make in it

Hammers and beaters Blow bars Impact plates Grinding paths Grizzly bars Mill liners Diaphragms and discharge grates Feed chute liners Mill feed spouts

High-chromium white iron

Chromium–molybdenum white irons, typically 15–28% Cr.

ASTM A532 Class II and IIIIS 4771ISO 21988 / EN 12513

Chemistry: About 2–3.6% carbon with 11–30% chromium, plus molybdenum, nickel or copper so that heavy sections harden through.
Hardness: Typically 550–700 HB (about 58–64 HRC) after hardening.
Heat treatment: Destabilised at high temperature, air-hardened and tempered.
Strength: Hard chromium carbides in a martensitic matrix give the longest life against sliding and low-stress abrasion.
Limits: Low impact toughness: not for tramp metal or heavy blows. Thick sections need the alloy and heat treatment designed together.

Parts we make in it

Blow bars Impact plates Grinding paths VRM rollers Table liners Mill liners Diaphragms and discharge grates Feed chute liners Mill feed spouts

Ni-Hard (nickel-chromium white iron)

Ni-Hard 1, 2 and 4 types.

ASTM A532 Class IIS 4771ISO 21988 / EN 12513

Chemistry: About 2.5–3.6% carbon with 3–7% nickel and 1.4–11% chromium; Ni-Hard 4 is the higher-chromium type.
Hardness: Typically 500–650 HB.
Heat treatment: Stress-relieved or hardened, depending on type and section.
Strength: Hard and abrasion-resistant, with a long service record in coal grinding.
Limits: Low impact toughness, like all white irons. Usually outlasted by high-chromium iron in pure abrasion.

Parts we make in it

VRM rollers Table liners Mill liners Feed chute liners

Heat-resistant steels

Cr-Ni types HH (25Cr-12Ni), HK (25Cr-20Ni) and HP40Nb (25Cr-35Ni, niobium-modified), high-chromium heat-resistant steels and stainless grades. Nickel and chromium can be tailored to the duty, subject to a feasibility review.

IS 4522IS 519ASTM A297ASTM A447EN 10295

Chemistry: HH: about 25% chromium and 12% nickel. HK: about 25% chromium and 20% nickel. HP40Nb: about 25% chromium and 35% nickel with niobium, for the highest temperatures and carburising gas. Where the duty needs it, we tailor nickel and chromium beyond the standard ranges after a feasibility review. Chromium forms the protective oxide; nickel keeps the structure austenitic and strong at temperature.
Temperature: Holds its shape and resists scaling at temperatures that would burn ordinary steel away. Typical limits in oxidising service are about 1,100 °C for HH and 1,150 °C for HK.
Heat treatment: Usually supplied as cast. Chemistry is held to tight limits because it sets life at temperature.
Limits: Thermal cycling, load and sulphur lower the practical limit. Long service at 650–900 °C can embrittle some HH types. That is why the choice between HH and HK is made by position.

Parts we make in it

Tip castings and sectors BRD segments Dip tubes Dispersion plates Grate bars and cross bars Grate and cooler plates Cooler conveying elements

Carbon and low-alloy steels

Structural cast steels, normalised or quenched and tempered.

ASTM A27ASTM A148IS 1030IS 2644EN 10293

Chemistry: Plain carbon and low-alloy steels with manganese, chromium, nickel and molybdenum as the strength class requires.
Hardness: Typically 150–300 HB as normalised; higher when quenched and tempered.
Heat treatment: Normalised, or quenched and tempered to the specified strength.
Strength: Strength, toughness and weldability for parts that carry load, locate other parts or are machined to fit.
Limits: Not a wear grade on its own: where it meets abrasion, the design protects or hardens the surface.

Parts we make in it

Toggle plates Crusher heads and sockets Clamps Trunnions Grate bars and cross bars Grate and cooler plates Track shoes Apron pans and sprockets Wheels and rollers Cooler conveying elements

Typical values from ASTM, IS, ISO and EN standards. Final chemistry and properties are agreed for each order and reported with the casting.

Seven mistakes when buying wear castings

And what to ask your foundry instead.

Grade picked by habit, not by dutyMatch the alloy to the feed, the impact and the temperature the part will meet.
Manganese steel quenched too slowlyA slow transfer from furnace to water leaves brittle carbides.
No method before the patternGating and feeding should be designed and simulated for critical parts, before metal is poured.
Wrong alloy in the hot zoneHH and HK look alike on a drawing. Ask for the spectrometer report against the heat.
Raw tolerances acceptedProof-machine and check the fit, so the part installs first time in a shutdown.
No record of the heatInsist on chemistry, hardness and NDT reports traceable to the heat number.
Waiting on overseas lead timesWork with a foundry that already holds your patterns.

Not sure which grade?

Tell us where the part works and how it fails today. A metallurgist will recommend the grade.

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