here are some of the steel materials used in USA excavator buckets:

• ASTM A572 Grade 50: This is a high strength, low alloy steel that is commonly used for the bucket shell. It is strong enough to withstand the forces of digging and loading, but it is also relatively lightweight.
  Photo from www.hicplates.com
• AR400: This is an abrasion resistant steel that is used for the bucket sides and cutting edge. It is harder than A572 Grade 50, which makes it more resistant to wear and tear.
  Photo from www.coremarkmetals.com
• T1: This is a high carbon steel that is used for the bucket teeth. It is very hard and wear resistant, which makes it ideal for digging into hard surfaces.
• Hardox: This is a high-performance wear plate steel that is used for excavator buckets in demanding applications. It is even harder than AR400, and it is also more resistant to impact.
  Photo from www.steels-supplier.com

The specific steel material used in an excavator bucket will depend on the application. For example, a bucket that will be used for digging in hard rock will need a harder steel than a bucket that will be used for loading sand.

In addition to the steel material, the design of the bucket also plays a role in its durability. A well-designed bucket will have features that help to distribute the forces of digging and loading, which can help to extend the life of the bucket.