AR450 abrasion-resistant plate: hardness, selection economics, equivalents

AR450 is the volume seller of the wear-plate range: 425–475 HBW, around 20–30 % more life than AR400. Where the step pays for itself, and where it does not.

Last updated 12 October 2026

What is AR450?

AR450 is the plate the wear-plate industry actually sells. Nominally 450 HBW, delivered in a band of about 425–475, it is the most widely stocked hardness in every major range — which matters commercially as well as technically, because the best-stocked thickness is often the cheapest per kilogram even when a softer plate would do.

The question with AR450 is never what it is but whether the step up from AR400 pays. The arithmetic is more interesting than it looks. In pure sliding abrasion AR450 returns roughly 20–30 % more life, for perhaps 5–15 % more per tonne. On a flat bolt-in liner that is replaced three times a year, that is an obvious gain: the plate cost is a small part of the total and the saved downtime and labour are the real prize.

On a formed and welded part the arithmetic inverts. Every fabrication parameter is worse at 450 HBW — the minimum bend radius goes from about 3 × thickness to 3.5–4 ×, the preheat threshold drops from roughly 20 mm to 15 mm, cutting is slower, drilling is harder, and the guaranteed impact energy is lower just when the part needs it. That penalty is paid once per part manufactured, while the wear saving is collected once per plate change. A complex formed chute made twice a year will usually be cheaper in AR400; a flat skirt plate changed monthly will usually be cheaper in AR450.

The second thing that changes at this hardness is the dominant failure mode. At 400 HBW most wear parts wear out. At 450 a larger share crack or chip instead — from a bend radius that was too tight, a hardened thermal-cut edge that was never ground, a hard weld filler, or impact the plate was not tough enough for. This is why every major producer offers a high-toughness variant at the same hardness (Hardox 450 HiTuf and its counterparts), and why specifying a guaranteed Charpy figure rather than a typical one is worth doing at this level and optional at 400.

As with the rest of the class, no standard defines AR450 — see the AR400 page for what the designation does and does not mean, and the proprietary-grades page for how to write a specification that several mills can quote.

AR450 chemical composition

**Indicative ceilings across the AR450-class products, not a specification** — no standard defines the grade and each producer declares its own analysis. Compared with the 400 class the carbon ceiling rises slightly and the chromium, nickel and molybdenum allowances rise more, because the quench has to produce a higher hardness through the same thickness. The practical effect on a fabricator is the **carbon equivalent**, which runs higher and pushes the preheat threshold down.

AR450 mechanical properties

Hardness is the sold property; the tensile numbers follow from it and are usually published as typical. The rows that decide whether this plate can be used for a given part are the last three — **impact energy, bend radius and preheat threshold** — and all three are worse than at 400 HBW. A quotation that lists only the hardness band has not told you what you need to know.

Impact toughness

AR450 requires a minimum Charpy V-notch energy of 27–40 J longitudinal standard product; 45–65 J for high-toughness variants J at −40 °C °C (No standard applies, so whether a figure is guaranteed or merely typical is a commercial matter. The high-toughness variants of this hardness class exist precisely because the standard product's toughness is marginal for impact-loaded parts such as rock boxes and crusher chutes.). At 450 HBW the toughness margin is narrower than at 400, and more of the field failures in this class are chipping and cracking rather than wear. Where the duty includes impact, either specify the high-toughness variant or step back to AR400.

AR450 equivalent grades

Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for AR450 →

Old and superseded designations

Product forms and tolerance standards

Product forms: hot-rolled quenched and tempered plate, typically 3 to 80 mm (widest stock range of the class), profile-cut parts and laser or plasma cut blanks, press-brake formed liners and chutes, wear strip, round bar and tube in some ranges, high-toughness variants for impact duty (HiTuf, HT and similar designations).

Dimensional tolerances: thickness and flatness: EN 10029 or ASTM A6, normally ordered to a tighter flatness class than normal; hardness: the producer's own band, measured through thickness; for cut parts, the contour tolerance is the cutter's, not the mill's — specify it separately.

Key property values

AR450 hardness and wear life

425–475 HBW as delivered, nominally 450, about 47 HRC. Against S355 structural plate at 150 HBW it returns roughly four to five times the life in sliding abrasion; against AR400 the gain is 20–30 %. Those multipliers hold only where the abrasive is harder than the plate and the mechanism is sliding. Measure through thickness, not at the surface.

When the step from AR400 pays

Run the comparison on cost per tonne of material moved, not on plate price. The step pays when the part is simple (flat or single-bend), frequently replaced (so the wear saving is collected often), and bolted rather than welded (so no welding penalty). It does not pay when the part is complex (multiple tight bends, welded assembly), long-lived (the wear saving arrives once a decade), or impact-loaded (where the lower toughness is a liability rather than a cost). The fabrication penalty is per part made; the wear gain is per plate changed.

Forming at 450 HBW

Minimum inner bend radius rises to about 3.5–4 × thickness transverse to the rolling direction and 5–6 × parallel to it. Three precautions become mandatory rather than advisable: grind the thermal-cut edges in the bend zone, because the hardened and notched cut edge is where the crack starts; form at room temperature or above, never on cold plate from an outside rack; and orient the bend across the rolling direction wherever the layout allows. A cracked bend at this hardness is almost always one of those three, not a material fault.

Welding window

Carbon equivalent runs higher than at 400 HBW, so the preheat threshold drops to roughly 15 mm for a single plate and lower for combined thicknesses — the producer's own table governs and should be followed rather than interpolated. Low-hydrogen consumables, filler softer than the plate, moderate heat input, no post-weld heat treatment. The softened heat-affected zone is wider in proportion than at 400 HBW, so designs that place a weld seam in the wear path fail faster here; plug welding, bolting and weld-on wear buttons are the normal answers.

The high-toughness variants

Every major range offers a version at the same hardness with substantially higher impact energy — typically 45–65 J at −40 °C against 27–40 J for the standard product — achieved through cleaner steel, tighter segregation control and a modified quench. They cost more and are stocked in fewer thicknesses. They are the right answer for thick-section impact parts: rock boxes, crusher feed chutes, grizzly bars, truck body floors taking large lump drop. For sliding abrasion with no impact they add nothing.

Alternatives at the same performance level

Two genuinely different routes reach AR450 performance. Work-hardening plate (Creusabro 4800 and similar) is delivered at about 370 HBW — so it forms, cuts and drills like a softer plate — and hardens to 440–470 HBW in service. It is attractive for complex formed parts and less so where the wear is light enough that it never fully hardens. Austenitic manganese steel at 12–14 % Mn is delivered soft and work-hardens past 500 HBW at the surface, but only under heavy impact; it is the material of crusher jaws and rail frogs and is poor in pure sliding abrasion. Choose by mechanism, not by hardness number.

Weldability

As for the 400 class but with less margin. Low-hydrogen consumables, a filler softer than the plate, moderate heat input and interpass temperature, and no post-weld heat treatment under any circumstances. The difference is the preheat threshold: roughly 100 °C above 15–20 mm single-plate thickness, and lower again where combined thickness is high or the joint is restrained — use the producer's table rather than a rule of thumb, because the carbon equivalents differ between brands at this hardness. Hydrogen control matters more here: dry the electrodes, clean the joint, and do not weld damp plate. Expect a proportionally wider softened heat-affected zone, and design the joint out of the wear path.

Machining, forming and heat treatment

Slower and harder than AR400 throughout: roughly 25–30 % machinability relative to 1 % C free-cutting steel. Carbide tooling only for anything beyond a single hole, rigid set-ups, low speeds, firm uninterrupted feed. Drilling at 475 HBW is at the limit of cobalt HSS and should be done with carbide; punching is out of the question and plasma or waterjet cutting is the normal route for holes. Thermal cutting leaves a 2–4 mm hardened edge that must be ground where the part is formed or fatigue loaded. Grinding is routine. Where a threaded fixing is needed, weld a boss rather than tap the plate.

Typical applications

• Tipper and dump body floors and sides (the volume application of the class)
• Bolt-in liners for chutes, hoppers, bins and transfer points
• Conveyor skirts, scrapers, deflectors and impact plates
• Excavator and loader bucket liners, side cutters and wear strips
• Screen decks, feeder pans and grizzly bars (high-toughness variant)
• Recycling and shredder wear parts, baler liners
• Cement, quarry and mining plant wear components

Frequently asked questions

Related grades

Verified against ; EN 10029 (plate thickness and flatness tolerances); ASTM A6/A6M (general requirements for rolled plate); EN 10025-6 (S690QL comparison). Last checked: October 2026.