Crusher wear parts: choosing between Mn13, Mn18, Mn24 and high-chrome iron

The question is not "which grade", it is "which mechanism"

Hadfield manganese and high-chrome white iron do not compare: they address two opposite wear mechanisms. The first work-hardens under impact and absorbs blows without fracturing; the second is hard as cast and resists abrasive rubbing, but is brittle. Choosing starts with identifying what actually destroys your part.

Two symptoms are enough to orient the diagnosis. A part that cracks, deforms or breaks is working under an impact its alloy cannot take. A part that thins steadily without breaking is under pure abrasion and lacks hardness. The first calls for manganese, the second for high-chrome iron. Mixed duties — the majority — require a trade-off.

Manganese steels: hardening by working

Austenitic manganese steel, known as Hadfield, is covered by ASTM A128. Its distinctive behaviour is to leave the foundry relatively soft — on the order of 200 HB — then work-harden at the surface under repeated impact, climbing past 500 HB while keeping a tough core. That hard-skin / ductile-core combination is what lets it take rock without fracturing.

The manganese trap is the absence of impact. On a purely abrasive duty — a chute liner, sliding wear from fines — Hadfield never work-hardens, stays soft and wears fast. This is the most common error: ordering Mn13 "because that's what we always take" for a duty where it cannot work.

High-chrome white irons: hard from the mould

High-chromium white irons fall under ASTM A532, which distinguishes classes by chromium content and alloying elements. Their high hardness comes from chromium carbides present from solidification: they need no impact to perform.

They excel at low-impact abrasion: impact crusher blow bars on soft to medium rock, hammer mill hammers, slurry pump impellers and casings, chute liners, cyclone components.

Their limit is brittleness. A high-chrome iron subjected to violent or repeated shock cracks and breaks. On a primary crusher taking rock, it is the wrong choice regardless of its hardness.

Mixed duties: where the real decision lives

Most equipment is neither purely abrasive nor purely impact-driven. Three ways to arbitrate:

• Bimetal. A hard high-chrome layer cast onto a ductile steel backing. You get abrasion resistance at the surface and impact tolerance underneath. Higher cost, but often the best value on mill liners.
• Heat-treated alloy steel. A reasonable compromise when neither Hadfield nor high-chrome fits, with hardness adjustable through heat treatment.
• Bonded ceramic composite. For severe abrasion at low impact, bonded ceramic protection can outperform any foundry grade — the subject of our comparison, alumina ceramic versus AR steel.

Unit price is the wrong indicator

A part 30% cheaper that lasts 40% less costs more, and that arithmetic still ignores the real expense: the production stoppage to change it. On a crushing circuit, downtime routinely exceeds the price of the part itself.

The indicator that decides is cost per tonne processed: part price, plus replacement labour, plus the valued cost of downtime, divided by the tonnage actually passed. It is the same ownership-cost logic applied to coating systems, and it regularly reverses the ranking of quotations.

Calculating it needs one figure few plants keep: actual tonnage between replacements. Rudimentary wear tracking — thickness measured at three dates, tonnage logged — is enough to establish the curve and predict the next interval.

What a good supplier delivers with the part

• Material certificates tied to the delivered heat: chemical composition and mechanical tests, not a generic grade sheet.
• Dimensional records, and a CMM inspection report for fit-critical parts — a dimensional deviation is paid for in fitting hours during the shutdown.
• Heat traceability, so two successive orders are comparable.
• A lead time that is held and aligned to your shutdown window. A part delivered after restart has no value.

FAQ

Is Mn18 always better than Mn13? No. Higher manganese only pays where the impact energy justifies the additional work-hardening. On a moderate-impact duty, Mn18 costs more without lasting longer.

Can Hadfield manganese be welded? Yes, but carefully: manganese steel is sensitive to heat input, which embrittles it through carbide precipitation. Procedures impose limited heat input and controlled cooling, with matched consumables.

Why does my high-chrome blow bar keep breaking? Almost always because the duty carries an impact the alloy cannot tolerate — oversized feed, tramp metal, irregular feeding. That is a selection or feed problem, not a casting quality problem.

What lead time should we expect on foundry castings? It depends on grade, pattern availability and the foundry's order book. The useful rule is to order against the shutdown window, not against observed wear: placing the order once the part is already marginal guarantees an unplanned stoppage.

How do we find out which grade is currently fitted? Positive material identification on the worn part answers in minutes, and a hardness test completes the picture. Without that data, any life comparison between two suppliers is unsound.

Having your wear parts specified on the right criterion

Induscoat commercializes foundry castings and wear parts for crushers, mills and material handling — mantles, concaves, jaw plates, blow bars, liners — with the grade selected against your ore, your impact profile and your target life, backed by material certificates. Send us the worn part, its position in the circuit and your tonnage between replacements: we will tell you whether the current grade is the right one, including when the answer is yes. Start from our foundry castings and wear parts page or our quote request: reply within 24 business hours. Technical data sheets for the Induscoat range are published on the brand site, induscoat.com.