Abrasion-resistant (AR) steel plate is a type of quenched and tempered steel specifically engineered for superior hardness and wear resistance. It’s designed to withstand constant friction, gouging, and impact in demanding environments — the kinds of conditions that quickly wear down regular carbon steel.

What Is Abrasion Resistance Plate?

AR plate achieves its toughness and hardness through a high-carbon alloy composition and a quench-and-temper heat-treatment process. This combination forms a microstructure that resists abrasion and extends service life, even under severe mechanical wear.

While all AR plates are designed for hardness, they are not created equal. They come in various grades defined by Brinell Hardness Number (BHN) — commonly AR200, AR235, AR400, AR450, AR500, and AR600. The higher the number, the greater the wear resistance (and the lower the ductility).

Common trade names and brands include:

• Hardox® (SSAB)
• Abrasion-Resistant (AR) 400 / AR500 / AR600 (various mills)
• Quard® (NLMK)
• Raex® (SSAB)
• Wearalloy® (JADCO)
• XAR® (ThyssenKrupp)
• Brinell® and QT-100 variants

Where Abrasion Resistant Plate Is Used

AR plate is found in any application where components face severe wear, sliding, or impact. It’s not intended for structural use because its high hardness reduces ductility, making it susceptible to brittle fracture under stress.

Typical applications include:

• Mining and quarry equipment: hoppers, chutes, crushers, and screens
• Construction machinery: bulldozer and backhoe buckets, blades, and teeth
• Material handling systems: conveyors, draglines, and dump liners
• Transportation and agriculture: gravel trucks, plow shoes, and grain handling systems
• Defense: body armor and ballistic plates
• Industrial plants: grates, mixers, and impact liners

Even though AR plate isn’t meant for load-bearing structures, it’s very common to weld it to other steels — either to itself or to mild steel such as ASTM A36 — when fabricating or repairing wear components.

Because of its high hardness and low ductility, AR plate is susceptible to hydrogen-induced cracking (also called hydrogen-assisted cracking or cold cracking). The key to welding AR plate successfully lies in controlling hydrogen, heat, and stress.

Below are the six essential steps to weld AR plate successfully — and avoid cracking.

1. Use Low-Hydrogen Consumables

Always use low-hydrogen electrodes or filler metals, typically designated with –H2 or –H4 suffixes.

These designations indicate the deposited weld metal will contain no more than 2 or 4 mL of hydrogen per 100 grams of weld metal. Keeping hydrogen levels low minimizes the risk of hydrogen-induced cracking, especially in highly hardened zones.

2. Preheat

Preheating AR plate slows the cooling rate, reducing the chance of forming martensite — a hard, brittle microstructure that promotes cracking.

Follow the manufacturer’s recommended preheat temperature carefully, which depends on plate grade and thickness. Avoid excessive preheat, as it can temper (soften) the base material and reduce its wear resistance.

3. Slow Cool

Allow the welded part to cool gradually. Preheating naturally slows the cooling rate, but you can reduce the cooling rate further by covering the weld with insulating or heat-resistant blankets. Slow cooling minimizes thermal stress and prevents hard, brittle zones in the heat-affected area.

4. Use Undermatching Filler Metal (When Permitted)

A common mistake is assuming the filler metal must match the tensile strength of the AR plate.

In most cases, this isn’t necessary. Instead, use an undermatching filler metal — for example, a 70 ksi or 80 ksi filler. The resulting weld will be more ductile, helping absorb stress and reduce cracking risk in high-restraint joints.

If additional weld strength is required, simply increase the weld size (fillet or PJP) rather than using higher-strength filler.

5. Minimize Weld Restraint

Whenever possible, minimize restraint — both internal and external.

• Internal restraint relates to filler metal selection (use more ductile filler to allow some flexibility and reduce residual stresses).
• External restraint relates to joint design and part geometry.

Thicker sections and large assemblies restrict movement during cooling, increasing residual stress. While you may not always control the design, you can still minimize restraint by sequencing welds properly and using undermatching filler metals.  Residual stresses can be aleviated by stress relieving, but this may negatively impact the abrasion resistance properties of the AR plate. It is also another operation so the cost goes up as well.

6. Peen the Weld

Peening the weld after each pass helps reduce tensile residual stresses by introducing compressive stresses into the weld metal. This can significantly lower the likelihood of cracking, especially in joints under high restraint or when welding thicker plates.

What if the weld needs to be abrasion resistant as well?

If the final weld surface needs abrasion resistance, a hardfacing electrode can be used on the final layer.

However, note that some hardfacing electrodes require preheat temperatures that may exceed the AR plate manufacturer’s limits. In those cases, apply a buffer layer between the AR base plate and the hardfacing layer.

Always follow the AR plate manufacturer’s recommendations for the correct electrode and preheat range.

Keep this in mind when welding abrasion resistant plate

Welding AR plate successfully is all about controlling hydrogen, temperature, and stress.
By following these six practices — using low-hydrogen consumables, applying proper preheat, ensuring slow cooling, selecting undermatching filler, minimizing restraint, and peening the weld — you can dramatically reduce the risk of cracking.

Understanding the properties of AR plate and applying proper welding technique ensures you preserve its wear resistance and mechanical integrity while achieving a sound, durable weld.

Reference: Metals and How to Weld Them, 2nd Edition