AR500 abrasion-resistant plate: hardness, fabrication limits, equivalents
AR500 is the hardest wear plate that can still be fabricated: 470–530 HBW, bend radius about 5 × thickness. Its limits, why it is not armour plate, and what to use above it.
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What is AR500?
AR500 is the last hardness in the wear-plate range that can still be fabricated, and understanding it means understanding where the limits fall. At a nominal 500 HBW — delivered around 470–530, roughly 50 HRC — it gives about five to six times the sliding-abrasion life of S355 structural plate and some 15–20 % more than AR450.
Everything else about it is worse. The minimum inner bend radius rises to roughly 5 × thickness, against 3 × for AR400. Preheat becomes mandatory from about 10 mm rather than 20. Guaranteed impact energy, where it is guaranteed at all, falls to 20–30 J at −40 °C, and the high-toughness variants that exist at 450 HBW thin out sharply above it, because the metallurgy that buys toughness and the metallurgy that buys 500 HBW work against each other. The available thickness range narrows too, because a mill can only quench so deep so hard. In practice AR500 is specified for flat, bolted, sliding-wear liners and avoided for anything that must be formed into a shape or welded into a structure.
That leads to the selection rule that matters most at this hardness: the harder plate does not always last longer in service. Where there is impact, AR500 chips and AR450 does not, and a plate that chips loses material far faster than one that abrades. Where the abrasive is softer than the plate, the extra hardness does almost nothing because the abrasive is being crushed rather than cutting. AR500 earns its place in heavy sliding abrasion by hard rock, and loses it almost everywhere else.
Finally, a point that causes real confusion and occasionally real harm. AR500 is not armour plate. The name is widely used for steel shooting targets, and "Armox 500T" sounds like the same thing, but a protection plate is a different product: specified to ballistic acceptance criteria, with controlled through-thickness hardness, high guaranteed toughness, cleanliness to a protection standard, and testing against MIL-DTL-46100 or MIL-DTL-12560 class requirements. AR500 meets none of those and must never be substituted into an armour specification. For targets it is the conventional material, but that is a commercial usage of the same plate, not a protection rating — and the plate's own distance, calibre and angle limits come from the target maker, not from the steel.
AR500 chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | ≤ 0.3 | |
| Si | ≤ 0.7 | |
| Mn | ≤ 1.6 | |
| P | ≤ 0.025 | |
| S | ≤ 0.01 | |
| Cr | ≤ 1.5 | |
| Ni | ≤ 2.5 | |
| Mo | ≤ 0.8 | |
| B | ≤ 0.005 |
**Indicative ceilings across the AR500-class products, not a specification** — no standard defines the grade. The carbon ceiling reaches about 0.30 % and the nickel and molybdenum allowances roughly double against the 400 class, because 500 HBW through a 40 mm plate demands a much deeper hardening response. The consequence for the user is a **carbon equivalent that is no longer comfortable**: preheat becomes the rule rather than the exception, and the welding window narrows to the point where many parts are designed to avoid welding altogether.
AR500 mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| AR500 class — hardness band as delivered | — | — | — | 470–530 HBW (typical, brand dependent) |
| Typical tensile properties at 500 HBW | 1250–1400 (181.3–203.1) | 1600–1750 (232.1–253.8) | 8 | ≈ 500 HBW |
| AR550 / AR600 classes — for comparison | 1400–1700 (203.1–246.6) | 1800–2100 (261.1–304.6) | 6–7 | 525–625 HBW |
| Charpy impact (where guaranteed) | — | — | — | 20–30 J at −40 °C, longitudinal — often typical rather than guaranteed |
| Minimum inner bend radius, transverse | — | — | — | ≈ 5 × thickness (6–8 × parallel to rolling) |
| Preheat threshold, single plate | — | — | — | ≈ 125–150 °C from about 10 mm (producer's table governs) |
The hardness and strength rows improve on the softer classes; **every other row gets worse**, and that is the real content of this page. Bend radius roughly doubles against AR400, the preheat threshold halves, the guaranteed impact energy falls to 20–30 J where it is guaranteed at all, and the available thickness range narrows. AR500 is specified for what it survives, not for what it can be made into.
Impact toughness
AR500 requires a minimum Charpy V-notch energy of 20–30 J longitudinal where guaranteed J at −40 °C °C (Several producers publish typical values only at this hardness, and some publish none. High-toughness variants exist at 450 HBW but thin out sharply above it, because the metallurgy that buys toughness and the metallurgy that buys 500 HBW pull in opposite directions.). This is the number that decides whether AR500 is the right answer. If the part sees impact, the toughness margin at 500 HBW is small and chipping becomes the failure mode — a tougher plate at lower hardness will usually last longer in service even though it tests softer.
AR500 equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| AR450 | Proprietary (trade names) | Near | 425–475 HBW: 15–20 % less abrasion life, and a far easier plate to work with — bend radius around 3.5–4 × thickness against 5 ×, preheat from 15–20 mm against 10 mm, and a genuine high-toughness variant available. For most formed or welded parts it is the better choice, and the selection economics are set out on that page. |
| AR400 | Proprietary (trade names) | Near | 370–430 HBW, the fabrication-friendly end of the class and the page that explains what AR designations mean, how hardness relates to wear, and how to specify wear plate without naming a brand. |
| 1.2379 | EN (European) | Functional | X153CrMoV12 (D2) at 58–62 HRC, about 700 HBW, with roughly 15 % carbide volume. The tool-steel route for small, high-wear inserts; not available or usable as a plate product. |
| S355J2 | EN (European) | Functional | EN 10025-2 S355J2 at roughly 150 HBW — the reference point. AR500 lasts about five to six times as long in sliding abrasion, and that multiplier is the whole reason to accept its fabrication penalties. |
| Armox 500T | Proprietary (trade names) | Functional | **Protection plate, not wear plate, despite the similar number.** Armox and its counterparts (Mars, Ramor, Secure) are specified to ballistic acceptance criteria with controlled through-thickness hardness, high guaranteed toughness and cleanliness to a protection standard, and are tested to MIL-DTL-46100 / MIL-DTL-12560 class requirements. An AR500 plate meets none of those requirements and must never be substituted for an armour specification. |
| Creusabro 8000 | Proprietary (trade names) | Functional | ArcelorMittal's work-hardening route against this class: delivered around 430 HBW and hardening to about 550–600 HBW in service. It forms, cuts and drills far more easily than a delivered-500 plate, which makes it the practical alternative where part geometry rules AR500 out. |
| Mn13 | Proprietary (trade names) | Functional | Austenitic manganese steel, delivered near 200 HBW and work-hardening past 500 HBW at the surface under heavy impact. Where the mechanism is **gouging** rather than sliding — crusher jaws and cones, rail frogs, hammer mill parts — it outlasts any martensitic plate, and it is poor in pure abrasion. |
| chromium carbide overlay | Proprietary (trade names) | Functional | A mild-steel backing plate with a welded chromium-carbide deposit at 600–750 HV. This is the normal answer above AR500 for sliding abrasion: the backing stays weldable and formable while the working face is far harder than any through-hardened plate. It cannot take impact and the overlay cracks by design. |
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 AR500 →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| Hardox 500 | SSAB trademark | The reference product of the class; Hardox 550 and 600 sit above it in limited thicknesses, and Hardox Extreme at around 650–700 HBW is a liner material only. Hardox is a registered trademark of SSAB. |
| XAR 500 / Dillidur 500 | ThyssenKrupp / Dillinger trademarks | Durostat 500 (voestalpine), Brinar 500 (Buderus). |
| Quard 500 / Raex 500 | NLMK / SSAB trademarks | Abrazo 500 (Ancofer), Everhard 500 (JFE). Creusabro 8000 (ArcelorMittal) is the work-hardening product sold against this class. |
| AR500 target plate | shooting-range trade usage | A separate commercial usage of the same name for steel shooting targets. It is the same class of plate, but the selection criteria are entirely different and it is **not** armour plate — see below. |
Product forms and tolerance standards
Product forms: hot-rolled quenched and tempered plate, typically 4 to 50 mm (thinner range than the softer classes), profile-cut parts, usually waterjet or plasma cut and used flat, wear strip and bar, harder variants at 550 and 600 HBW in some ranges, in limited thicknesses.
Dimensional tolerances: thickness and flatness: EN 10029 or ASTM A6; flatness is harder to hold at this hardness and should be ordered to a stated class; hardness: the producer's own band, measured through thickness; thickness availability is the real constraint — the harder the class, the narrower the range a mill can quench uniformly.
Key property values
AR500 hardness and what it returns
470–530 HBW as delivered, nominally 500, about 50 HRC. Roughly five to six times the sliding-abrasion life of S355 structural plate and 15–20 % more than AR450. The multiplier applies only where the abrasive is harder than the plate and the mechanism is sliding; in impact-dominated or soft-abrasive service it collapses. Measure through thickness.
Where the fabrication limits bite
Four numbers change the design. Bend radius ≈ 5 × thickness transverse and 6–8 × parallel, so most AR500 parts are used flat or with a single generous bend. Preheat from about 10 mm at 125–150 °C, with combined thickness pulling that lower. No post-weld heat treatment, ever — a stress-relief cycle tempers the plate below its purchase hardness. No punching, no tapping, no practical drilling in production; holes are waterjet or plasma cut, and threaded fixings are welded-on bosses. A part that needs several tight bends and a welded assembly should not be in AR500.
Why harder is sometimes shorter-lived
Three mechanisms reverse the hardness ranking. Impact: at 20–30 J the plate chips, and a chip removes more material in one event than hours of abrasion; AR450 with a guaranteed 40 J will outlast it on a crusher chute. Soft abrasive: against a particle softer than the surface, the particle deforms instead of cutting, and the difference between 450 and 500 HBW is negligible — most sand and most coal fall here. Gouging by large lumps: the surface is being ploughed rather than scratched, and work-hardening austenitic manganese steel, delivered at 200 HBW, outperforms every martensitic plate. Identify the mechanism before buying hardness.
AR500 is not armour plate
A protection plate is a different product sold against different criteria: ballistic acceptance testing, a controlled and narrow through-thickness hardness profile, high guaranteed toughness (because a brittle plate shatters rather than resisting), and cleanliness and segregation control to a protection standard — Armox, Mars, Ramor and Secure, qualified against MIL-DTL-46100 or MIL-DTL-12560 class requirements. AR500 carries no ballistic testing, no toughness guarantee in many ranges, and no standard at all. It must not be substituted into an armour specification. Its use for shooting targets is a separate commercial practice, and the calibre, distance and angle limits for a target come from the target maker's rating, not from the plate's hardness.
What to use above AR500
The through-hardened plate route effectively ends here. AR550 and AR600 exist in limited thicknesses and are liner materials — essentially unformable and barely weldable. Above that the practical answers change kind: chromium carbide overlay (a weldable mild-steel backing with a 600–750 HV deposit) for sliding abrasion; cast high-chrome iron for slurry pumps and mill liners; austenitic manganese steel for gouging impact; ceramic tile or rubber-ceramic composite for fine high-velocity abrasive; and tool steel inserts at 700 HBW for small, concentrated wear points. Each of these solves a problem a harder plate cannot.
Cutting and hole-making
Waterjet is preferred where no heat-affected zone is acceptable, and that is more often at this hardness because the thermal-cut edge zone — 3–5 mm of re-hardened, notched material — is a crack initiator in a plate with little toughness to spare. Plasma and laser cutting work and are the volume route; grind the edge wherever the part will be formed, fatigue loaded or welded near the cut. Oxy-fuel cutting on thick plate needs controlled preheat to avoid edge cracking. Drilling is impractical in production; use cut holes. Flame straightening is not an option — localised heating tempers the plate.
Weldability
Weldable, but with the narrowest window of the class and often designed around rather than used. Low-hydrogen consumables, filler clearly softer than the plate, preheat 125–150 °C from about 10 mm single-plate thickness and lower where combined thickness or restraint is high — the producer's table governs, and at this hardness the brands differ enough that interpolating is unwise. Hydrogen control is critical: dry consumables, clean dry joints, no welding on damp or cold plate. Keep heat input moderate and accept a proportionally wide softened heat-affected zone. No post-weld heat treatment under any circumstances. In practice AR500 parts are bolted, plug welded or fitted as loose liners, and the structure behind them is made of a weldable grade.
Machining, forming and heat treatment
Effectively a grinding-and-cutting material rather than a machining one: machinability around 20–25 % relative to 1 % C free-cutting steel. Production drilling, tapping, punching and shearing are all impractical at 500 HBW. Single holes can be made with carbide drills in a rigid set-up at low speed and firm continuous feed, but cut holes are the normal route. Milling and turning of cut edges is possible with carbide or CBN at very low speed. Grinding works normally and is the standard way to dress thermal-cut edges, which should be done on any part that will be formed, welded near the cut, or cyclically loaded. Flame straightening and local heating are prohibited — they temper the plate.
Typical applications
- Flat bolt-in liners for severe sliding abrasion — ore chutes, transfer points, rock boxes
- Dump and haul truck body liners in hard-rock mining
- Crusher and screen wear plates where impact is low
- Conveyor skirt and scraper blades in abrasive duty
- Cutting edges, side cutters and bucket lips (often with overlay or weld-on protection)
- Wear strips, slide plates and chute deflectors
- Steel shooting targets (commercial usage — see the note above; not armour)
Frequently asked questions
Is AR500 armour plate?
No. Armour, or protection plate, is a different product: specified to ballistic acceptance criteria with a controlled through-thickness hardness profile, high guaranteed toughness and cleanliness to a protection standard, and qualified against MIL-DTL-46100 or MIL-DTL-12560 class requirements. Products such as Armox, Mars, Ramor and Secure are in that category. AR500 has no standard at all, no ballistic testing and often no guaranteed toughness, and it must never be substituted into an armour specification.
What is the hardness of AR500?
Nominally 500 HBW, delivered in a band of roughly 470–530 HBW depending on the producer — about 50 HRC. Ask for a through-thickness measurement at a stated depth rather than a surface reading, because quenched plate reads high at the surface.
Can AR500 be bent?
Only to generous radii. The minimum inner radius is about 5 × thickness with the bend transverse to the rolling direction, and 6–8 × thickness parallel to it — roughly double what AR400 needs. Thermal-cut edges in the bend zone must be ground, the plate must be at room temperature or above, and the bend must run across the rolling direction. Most AR500 parts are designed flat or with a single large-radius bend for this reason.
Can AR500 be welded?
Yes, with the narrowest window of the class: low-hydrogen consumables, a filler clearly softer than the plate, and preheat of 125–150 °C from about 10 mm single-plate thickness and lower with combined thickness or restraint. Hydrogen control is critical and the producer's own table should be followed rather than interpolated. Never post-weld heat treat. In practice AR500 is usually bolted or plug welded as a liner rather than welded into a structure.
Does AR500 always last longer than AR450?
No. In heavy sliding abrasion by hard rock it gives 15–20 % more life. But where there is impact it chips, and a chip removes more material in one event than hours of abrasion, so AR450 with a guaranteed 40 J will outlast it. Where the abrasive is softer than the plate — much sand and coal — the extra hardness does almost nothing. And in heavy gouging, work-hardening manganese steel beats both. Identify the wear mechanism before buying hardness.
What should I use if AR500 is not hard enough?
Change kind rather than climbing further. Chromium carbide overlay gives a 600–750 HV working face on a weldable mild-steel backing and is the usual answer for severe sliding abrasion. Cast high-chrome iron suits slurry pumps and mill liners, austenitic manganese steel suits gouging impact, ceramic or rubber-ceramic composite suits fine high-velocity abrasive, and tool-steel inserts at 700 HBW suit small concentrated wear points. AR550 and AR600 exist but are liner materials — essentially unformable and barely weldable.
Can holes be drilled in AR500?
Single holes can be made with carbide drills in a rigid set-up at low speed and firm continuous feed, but production drilling is impractical and punching and tapping are out of the question. Holes are normally waterjet, plasma or laser cut, and threaded fixings are made by welding a boss onto the plate rather than tapping it.
Is AR500 the same as Hardox 500?
Hardox 500 is SSAB's product in this class and the usual reference, but AR500 is a trade description rather than a definition — another mill's AR500 may differ in analysis, guaranteed impact energy, bend radius, available thickness and tolerance class. To get comparable quotations, specify the through-thickness hardness band, the guaranteed impact energy and temperature, the bend radius at the ordered thickness and the tolerance class, rather than a brand name.
Related grades
Verified against ; EN 10029 (plate thickness and flatness tolerances); ASTM A6/A6M (general requirements for rolled plate); MIL-DTL-46100 / MIL-DTL-12560 (armour plate requirements, cited for contrast only). Last checked: October 2026.