Abrasion Resistant Steels

Wear, the undesired removal of material from contacting surfaces, is an extremely common phenomenon – tires, clothes, shoes, coins, floors, even the Earth experience wear. Unlike stress, wear is visible. It’s predictable. But inevitability doesn’t mean that we don’t have ways to combat it.

Many steel parts are designed to withstand stresses; increasing strength increases a material’s ability to resist bending, stretching, and twisting. The test used to determine strength, a tensile test, involves stretching a sample on a single axis until it breaks. But if we’re designing a part that isn’t bent, stretched, or twisted, and instead is subjected to abrasion and wear, we need to focus on hardness.

Strength and hardness are loosely correlated, but they are two different material properties. Strength is a material’s ability to withstand an applied load without plastic deformation, and hardness is a resistance to localized plastic deformation, or indentation.

Most steel parts that experience wear experience it as abrasion – hard particles, sometimes under pressure, roll and slide on a surface. Increasing the steels hardness increases its ability to withstand abrasion and erosion, allowing it to last longer and extending its service life.

A group of steels, called abrasion resistant (AR) steels, are designed to have high hardness. There are no national standards governing these grades, so each steel mill sets its own parameters for chemistries and material properties. OEMs also publish standards to define AR grades. Hardness is measured on the Brinell hardness scale, and is given as a nominal number, usually +/- about 50. For example, AR450 would have a hardness range from about 400 BHN to 500 BHN.

AR steels are not intended for structural and load bearing applications. 

Some popular AR grades are listed below: