7226.91 - Not further worked than hot-rolled:

This HTS category, 7226.91, encompasses flat-rolled products of other alloy steel that are less than 600 mm in width and have undergone only hot-rolling. "Not further worked than hot-rolled" signifies that the material has been subjected to high temperatures during its rolling process but has not undergone subsequent cold-forming or additional finishing operations beyond those inherent to hot-rolling, such as descaling or trimming. These products are distinct from their siblings; specifically, they are differentiated from those classified under 7226.92, which are explicitly cold-rolled (cold-reduced).

The distinction between hot-rolled and cold-rolled products is crucial for classification. Hot-rolled steel typically exhibits a rougher surface finish and may have slight dimensional variations due to the process. Cold-rolled steel, in contrast, is rolled at or near room temperature, resulting in a smoother surface finish, tighter dimensional tolerances, and increased strength and hardness. The "other alloy steel" designation within this chapter signifies steel containing specific quantities of elements beyond iron and carbon, such as chromium, nickel, molybdenum, or vanadium, to enhance its properties.

The subcategories within 7226.91 further refine the classification based on the specific type of alloy steel. The primary subdivisions are "Of tool steel (other than high-speed steel)" and "Other." This indicates that a key criterion for breaking down this category is whether the alloy steel possesses the specific composition and properties characteristic of tool steels, which are designed for shaping other materials, or if it falls into a broader category of other alloy steels not meeting the precise definition of tool steel.