1.1 本规范 2. 涵盖淬火和回火合金钢螺栓、螺柱和其他4英寸外螺纹紧固件的化学和机械要求。在正常大气温度下应用，需要高强度，在高温下应用有限( 注1 ). 可以使用任何能够满足本规范中规定的机械和化学性能的合金钢。 注1: 对于高温下使用的螺栓、螺柱或其他外螺纹紧固件，请参阅规范 A193/A193M . 1.2 涵盖两个强度等级，指定等级BC和BD。选择将取决于设计、应力和产品使用的服务。 注2: 结构钢接头用淬火和回火合金钢螺栓 1. / 2. 在里面直径包含在规范中 F3125/F3125M . 对于直径大于1的紧固件 1. / 2. 在里面对于需要120 ksi以上抗拉强度的结构钢螺栓，可以考虑BC级，对于需要150 ksi以上抗拉强度的结构钢螺栓，可以考虑BD级。在这种情况下，规范的附加要求 F3125/F3125M 例如，应仔细考虑头部尺寸、润滑剂和磁粉检查。 1.3 螺母包含在规范中 A563型 . 除非另有规定，否则每个紧固件等级的螺母等级和样式应如下所示: 紧固件等级和表面光洁度 螺母等级和 风格 A. BC，普通（或涂层厚度不足- 需要过攻丝螺母） C、 重型六角 BC，镀锌（或涂层厚度为re- 询问- 螺纹螺母） DH，重型十六进制 BD，所有饰面 DH，重型十六进制 1.4 本标准末尾提供了可选的补充要求。 1.5 本规范中使用的术语在术语中定义 F1789 除非本文另有规定。 1.6 以英寸-磅为单位的数值应视为标准值。本标准不包括其他计量单位。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。

1.1 This specification 2 covers the chemical and mechanical requirements of quenched and tempered alloy steel bolts, studs, and other externally threaded fasteners 4 in. and under in diameter for application at normal atmospheric temperatures, where high strength is required and for limited application at elevated temperature ( Note 1 ). Any alloy steel capable of meeting the mechanical and chemical properties set forth in this specification may be used. Note 1: For bolts, studs, or other externally threaded fasteners, to be used at elevated temperatures, refer to Specification A193/A193M . 1.2 Two strength levels are covered, designated Grades BC and BD. Selection will depend upon design and the stresses and service for which the product is to be used. Note 2: Quenched and tempered alloy steel bolts for structural steel joints up through 1 1 / 2 in. in diameter are covered in Specification F3125/F3125M . For fastener diameter sizes above 1 1 / 2 in., Grade BC may be considered for structural steel bolting where tensile strength above 120 ksi is necessary and Grade BD may be considered for structural steel bolting where tensile strength above 150 ksi is necessary. In this event, additional requirements of Specification F3125/F3125M , such as head size, lubricant, and magnetic particle inspection, should be carefully considered. 1.3 Nuts are covered in Specification A563 . Unless otherwise specified, the grade and style of nut for each grade of fastener shall be as follows: Grade of Fastener and Surface Finish Nut Grade and Style A BC, plain (or with a coating of insufficient thick- ness to require over-tapped nuts) C, heavy hex BC, zinc-coated (or with a coating thickness re- quiring over-tapped nuts) DH, heavy hex BD, all finishes DH, heavy hex 1.4 Optional supplementary requirements are provided at the end of this standard. 1.5 Terms used in this specification are defined in Terminology F1789 unless otherwise defined herein. 1.6 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.