... > SECTION XV - BASE METALS AND ARTICLES OF BASE METAL > CHAPTER 72 - IRON AND STEEL > IV. OTHER ALLOY STEEL; HOLLOW DRILL BARS AND RODS, OF ALLOY OR NON-ALLOY STEEL > 7224 Other alloy steel in ingots or other primary forms; semi-finished products of other alloy steel > Ingots and other primary forms > Of tool steel