How to rank abrasion protection by the wear test that matters — not by the hardness number on the datasheet.
Reviewed by Jitamitra application engineering
Share on LinkedInEvery fan that moves dust runs on a wear clock. The wheel and the scroll will erode — that is not the question. The question is whether the wear lands on a hard, replaceable surface, or on the parent metal of an impeller you will eventually scrap. Get that decision right and you change a liner; get it wrong and you change the fan. And the decision is almost always made on the wrong number.
Buyers compare wear protection by Rockwell hardness because it is the figure on every datasheet. But overlay hardness depends on how many passes were laid and how much the deposit was diluted by the base metal — quote a single HRC and you have told the reader almost nothing. The honest comparator is the ASTM G65 dry-sand abrasion test: material lost, in mm³, under a standard rubbing load. Lower volume loss wins. Ask for the G65 figure next to every hardness claim, and ask how many overlay passes the quoted HRC assumes.
The same discipline kills a common and expensive myth. 304/316 stainless buys you almost nothing against abrasion. It sits around 124–147 HBW — barely above mild steel. Stainless solves corrosion; it is not a wear material. If your dust extraction or pneumatic conveying duty is erosive rather than wet-corrosive, specifying stainless "for durability" is money spent on the wrong problem. For wear you need AR plate, an overlay, or ceramic.
There is no single best surface — there is a best match to the abrasion severity, the geometry, and the temperature.
| Method | Typical hardness | Where it fits |
|---|---|---|
| AR plate (AR400/450/500 class) | ~400–500 HBW | Moderate abrasion where the whole wheel or liner can be one weldable, formable material. Wears uniformly; easy to repair in the field. |
| Hardfacing overlay (chromium-carbide, CCO) | 55–59 HRC single up to ~63 HRC multi-layer |
Severe abrasion — fly-ash, cement, aggressive conveyed solids. A hard skin on a tough backing. Longest practical life on harsh duty. |
| Ceramic lining (alumina / SiC tile) | — | Extreme fine-particle erosion where temperature and impact allow. Longest life, highest cost, brittle. |
Two details decide more jobs than the hardness spec does. First, chromium-carbide overlay cannot be oxy-cut or conventionally machined — it is plasma- or abrasive-cut and formed before overlay where possible, so it is applied where it will stay, not shaped afterwards. Complex-carbide grades push to 61–64 HRC but carry a service-temperature ceiling (around 450 °C); tungsten-carbide applied by PTA covers the most severe small zones, such as blade leading edges.
Second, the ceramic trap. A bonded ceramic tile is limited by its epoxy or rubber bond line — roughly 150–300 °C — not by the 1,000 °C-plus rating of the ceramic itself. If ceramic is quoted, the number that matters is the bond-line temperature limit. Always ask whether your duty sits inside it.
Jitamitra runs chromium-carbide hardfacing by FCAW at 55–60 HRC as the standing treatment for fly-ash erosion, using the high-chromium EFeCr-A consumable family (AWS A5.13/A5.21), and carries wear plates and impeller wear protection as preferred base scope on the radial families that take the dirtiest duty. Because any overlay adds mass to a spinning wheel, every overlaid impeller is re-balanced as a mandatory step — a hard surface is worthless if it introduces vibration. Welding and overlay are controlled to an internal procedure with recorded grade, pass count and coverage, and 100% visual inspection of critical impeller welds.
Wear protection is engineered against your stated dust loading and its nature — abrasive, sticky, hot, fine or coarse. State them in the RFQ and the wear package comes back sized to the duty, not guessed from a hardness number.
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Jitamitra Electro Engineering · Fan-engineering notes, written for the engineer.
Sources & basis. Figures reflect Jitamitra's standing wear-protection and welding/overlay practice and the material datasheets for the materials cited — chromium-carbide hardfacing by FCAW at 55–60 HRC as the standing fly-ash treatment, AR400/450/500 (~400–500 HBW), CCO 55–63 HRC, complex-carbide 61–64 HRC (~450 °C ceiling), 304/316 stainless at 124–147 HBW, ceramic bond-line 150–300 °C, and the 20% blade-thickness change-out trigger. Wear grades are engineered per job; served ranges shown, not absolute guarantees. Standards named (ASTM G65, AWS A5.13/A5.21) are test/consumable references, not certification claims.
No. Stainless buys you almost nothing against abrasion — it sits around 124–147 HBW, barely above mild steel. Stainless solves corrosion; it is not a wear material. If the duty is erosive rather than wet-corrosive, specifying stainless for durability is money spent on the wrong problem. For wear you need AR plate, an overlay, or ceramic.
Not by hardness. Overlay hardness depends on how many passes were laid and how much the deposit was diluted by the base metal, so a single HRC tells you almost nothing. Ask instead for the ASTM G65 dry-sand abrasion figure — material lost, in mm³, under a standard rubbing load. Lower volume loss wins. Ask how many passes the quoted HRC assumes.
Chromium-carbide overlay is the home for severe abrasion — fly-ash, cement, aggressive conveyed solids — a hard skin on a tough backing, at 55–59 HRC single and up to about 63 HRC multi-layer. AR plate suits moderate abrasion, wears uniformly and repairs easily in the field. Ceramic is for extreme fine-particle erosion: longest life, highest cost, brittle.
The bond line, not the tile. A bonded ceramic tile is limited by its epoxy or rubber bond line — roughly 150–300 °C — not by the 1,000 °C-plus rating of the ceramic itself. If ceramic is quoted, the bond-line temperature limit is the number that matters. Always ask whether your duty sits inside it.
It can, which is why every overlaid impeller is re-balanced as a mandatory step — any overlay adds mass to a spinning wheel, and a hard surface is worthless if it introduces vibration. Note also that chromium-carbide overlay cannot be oxy-cut or conventionally machined, so it is applied where it will stay rather than shaped afterwards.
Our practice works to 20% blade-thickness erosion as the change-out trigger. We do not guarantee a life: wear grades are engineered per job, and the ranges shown are served ranges, not absolute guarantees. The standards named — ASTM G65 and AWS A5.13/A5.21 — are test and consumable references, not certification claims. State your dust loading and its nature in the RFQ.
Flow, static, gas temperature, application — or attach a spec, GA drawing or a multi-fan schedule. Engineer to engineer.
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