Understanding Abrasion and Wear-Resistant Steel (AR Steel)
Not all steels are the same. In fact, there are over 3,500 different grades of steel, each encompassing unique physical, chemical, and mechanical properties to make them ‘custom-tailored’ to suit specific applications. Even within certain groups of steel like Abrasion and Wear-Resistant steels (AR steel) there are many different grades, each with different chemistry and mechanical properties that yield different performance.
Countless Shades of Tough
To understand the variations that you can find in abrasion-resistant steel, let’s take a look at AR 400, AR 500, AR 550, and AR 600 types of abrasion-resistant steel.
Each of the numbers of these AR steel types refers to the hardness of the steel as measured on the Brinell hardness scale. But the processes used by the manufacturers of these AR steel grades can vary greatly, using different alloys, chemistry, and heat treatment to achieve the specified hardness, yield, tensile strength, and elongation of the final product. They’re all abrasion-resistant, and they all meet the Brinell hardness requirements, but they’re all made by very different practices.
What Makes Steel AR?
AR steel alloys are made from billets of steel containing different alloying elements such as carbon, manganese, chrome, nickel, and boron. Of all these alloys, carbon is the most important in making steel abrasion resistant, as it increases hardness and toughness. The AR steel is then produced by “Quenching and Tempering” (Q&T), during which the grain structure is changed to increase toughness and reduce brittleness.
Q&T is a 2 stage process: Quenching occurs when the steel is brought to a temperature of around 1500 degrees F and cooled with oil, water, or air. This process increases hardness. Tempering is the process or reheating the steel to around 300-700 degrees F which allows the steel to become more ductile.
While high-carbon alloys and Q&T treatment makes steel harder, it also reduces its tensile strength. Therefore AR steels are used in situations where abrasion, wear, tear and impact are the main problem, and not constant tension or pressure. As such, AR steels are not ideal for structural construction like beams in bridges and buildings. Common uses are in buckets, grates, chutes, conveyors, ore pockets, and armor for vehicles and targets.
Better Quenching for Better Steel
Most AR Steels are water quenched because it is the fastest, cheapest option. Our ENDURA and ENDURA Dual steels are oil quenched which, while being far more expensive and time consuming, has the advantage of developing a homogeneous microstructure (maintaining the ‘grain’ of the metal), significantly reducing susceptibility to tearing, shearing, gouging, and wear.
Water quenching, used by other AR steels, disrupts the grain, resulting in a microstructure that is like fallen “Pick-Up sticks”, making it more susceptible to gouging and tearing of the steel, speeding up wear and deforming the steel.
Finally, ENDURA, ENDURA Dual and Titus Manganese are work hardening, meaning that the more impacting they sustain, the harder they become. For example, ENDURA AR 430 has an initial hardness of 430 BHN but, as it withstands impacts, it will harden up to 560 BHN. That’s an increase in hardness of 30%. Titus Manganese will work harden from 280 BHN to 550 BHN—which is an increase in hardness of over 200%.
If you need abrasion or wear-resistant steel materials, give us a call and let us know the application, conditions, and what you need out of your steel components. Our team will work with you to recommend the unique variety of steel that is perfectly suited to your application.