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Sub‑Chapter IV OTHER ALLOY STEEL; HOLLOW DRILL BARS AND RODS, OF ALLOY OR NON‑ALLOY STEEL
GENERAL
Other alloy steel is defined in Note 1 (f) to this Chapter and hollow drill bars and rods in Note 1 (p) to this Chapter.
This sub‑Chapter covers alloy steel other than stainless steel, in the form of ingots or other primary forms, semi‑finished products (e.g., blooms, billets, rounds, slabs, sheet bars, pieces roughly shaped by forging), flat‑rolled products, whether or not in coils (so‑called wide‑flats, wide coil, sheets, plates or strip), bars and rods, angles, shapes or sections, or wire.
All these products may be worked provided that they do not thereby assume the character of articles or of products falling in other headings (see the Explanatory Notes to headings 72.06 to 72.17).
The metals most commonly present in other alloy steel are manganese, nickel, chromium, tungsten (wolfram), molybdenum, vanadium and cobalt; the most common non‑metal additive is silicon. These alloying materials confer special properties to the steel, e.g., resistance to shock and wear (e.g., manganese steels); improved electrical qualities (silicon steels); improved tempering qualities (e.g., vanadium steels); or increased cutting speed (e.g., chrome‑tungsten steels).
Other alloy steels are used for many purposes requiring special qualities (e.g., durability, increased hardness, resilience, strength), for example, in armaments, tools and cutlery, and machinery.
Alloy steels of this sub‑Chapter include :(1) Alloy engineering and structural steels usually containing the following elements : chromium, manganese, molybdenum, nickel, silicon and vanadium. (2) Alloy steels having improved tensile strength and welding properties containing in particular very small quantities of boron (0.0008 % or more by weight) or of niobium (0.06 % or more by weight). (3) Alloy steels, containing chromium or copper, which are weather resistant. (4) Alloy steels for so‑called "magnetic" sheets (having a low magnetic loss) generally containing 3 to 4 % of silicon and possibly aluminium. (5) Free‑cutting alloy steels which not only conform to the requirements of Note 1 (f) but also contain at least one of the following elements : lead, sulphur, selenium, tellurium or bismuth. (6) Alloy bearing steels (generally containing chromium). (7) Alloy manganese silicon spring steels (containing manganese, silicon and possibly chromium or molybdenum) and other alloy steels for springs. (8) Non‑magnetic alloy steels resistant to shock and abrasion, having a high manganese content. (9) High speed steels : alloy steels containing, with or without other alloy elements, at least two of the three elements molybdenum, tungsten and vanadium with a combined content by weight of 7 % or more, 0.6 % or more of carbon and 3 to 6 % of chromium. (10) Non‑distorting tool steels : containing generally by weight 12 % or more of chromium and 2 % or more of carbon. (11) Other alloy tool steels. (12) Permanent magnet steels containing aluminium, nickel, and cobalt. (13) Non‑magnetic alloy steels which are characterised by their manganese or nickel content, other than those covered by sub‑Chapter III. (14) Steels for control rods in nuclear reactors (with high boron content). This sub‑Chapter also includes hollow drill bars and rods, of alloy or non‑alloy steel (heading 72.28).
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