This Standard specifies the classification and code, order content, size, shape, weight and allowable tolerance, technical requirements, test method, inspection rules, packaging, marking and quality certificate of alloy structure steel. This Standard applies to the hot-rolled and forged alloy steel bars which are not more than 250mm of nominal diameter or thickness. However, after negotiated by the Supplier and Demander, it is also allowed to supply hot-rolled and forged alloy steel bars which are more than 250mm of nominal diameter or thickness.