Why AR400 Steel is the Standard for Heavy-Duty Excavator Buckets

When shopping for excavator buckets, you'll frequently see the term "AR400 steel" listed in the specifications. But what exactly is AR400, and why does it matter for your equipment?

What Does AR Stand For?

AR stands for Abrasion Resistant. The number 400 refers to the steel's Brinell Hardness Number (BHN). Standard mild steel (like A36) has a hardness of around 120-160 BHN. AR400 is more than twice as hard, making it incredibly resistant to wear, gouging, and scraping.

Why Use It in Excavator Buckets?

Excavator buckets spend their lives grinding against rock, gravel, sand, and concrete. If a bucket were made entirely of mild steel, the cutting edge and side plates would wear thin and warp within a few months of heavy use.

Manufacturers use AR400 (and sometimes AR500) in high-wear areas—specifically the cutting edge, side cutters, and wear straps on the bottom of the bucket. This drastically extends the life of the attachment.

Is the Whole Bucket AR400?

Usually, no. AR400 is expensive and harder to weld and form than mild steel. High-quality buckets (like those from Gentec) use a strategic mix: mild steel for the main shell where flexibility and weldability are needed, and AR400 for the wear points that take the actual abuse. This provides the perfect balance of durability and cost-effectiveness.