Steel plate comes in a wide range of hardness. Hardness in steel can be defined as resistance to penetration. Abrasion resistant plate is manufactured to a Brinell hardness. Hardness is measured using a Brinell test. The smaller the indentation on the plate surface after the Brinell test means less penetration and the “harder” the plate surface. Hardness in steel is directly proportional to tensile strength. As hardness and strength increases, the formability and weld ability of steel decreases. Even though there is a direct correlation between steel hardness and tensile strength, mill producers will not certify to both.

There are two types of abrasion:
1. Impact abrasion — surface is worn away by chipping, spalling or cutting caused by hard materials striking the surface.
2. Sliding abrasion — surface is worn away by friction, such as sand sliding down a chute. There are no specific ASTM specifications for abrasion resistant (AR) steel. Over the years, steel producers, end users and wear plate distributions have developed trade names and specifications for a general group of applications that have become standard in the industry. Because there are no published standards there can be a great deal of flexibility in the chemistries used. AR steels are usually tested for surface hardness only.