LEXICONMaterials and finishes
Abrasion-resistant plate
Also called: Hardox, wear plate, AR plate, Raex, Dillidur, XAR
Quenched and tempered low-alloy steel specified by hardness rather than yield strength — typically 400 to 500 Brinell — used wherever sliding abrasion would destroy ordinary structural steel.
How it is made and rated
The plate is heated to austenitising temperature, quenched rapidly to form martensite and then tempered at low temperature to recover toughness. The result is graded by hardness: AR400, AR450 and AR500 are the common tiers, against roughly 120–180 HB for ordinary structural steel. Hardox is a Swedish trade name that has become generic; Raex, Dillidur, XAR and Brinar are equivalent products from other mills.
Working it, and why that matters
Hardness cuts both ways. The plate cannot be cut with conventional tooling — plasma, laser or abrasive waterjet only — and drilling needs carbide. Welding demands controlled heat input and often preheat, because the martensitic structure is sensitive to hydrogen cracking and the heat-affected zone softens locally. Cold bending has a minimum radius of several plate thicknesses. Every one of these constraints adds hours to any object built from it, which is a substantial part of why such work is expensive.
