1.1 本规范适用于直径大于等于4英寸[200毫米]主轴颈或曲柄销的锻钢曲轴的磁粉检测。 1.2 有三类，验收标准越来越严格: 1.2.1 第1类。 1.2.2 2级（最初是本规范的唯一验收标准）。 1.2.3 第3类（以前包含在规范的补充要求S1中 A456 – 64 (1970)). 1.3 本规范不适用于连续颗粒流曲轴（见规范 A983/A983米 ); 但是，规范 A986/A986M 可以用于此目的。 注1: 规格 a68/a68m 是一种产品规范，可用于通常扭曲以设置曲柄销角度的平板锻造曲轴锻件，或用于从圆柱形锻件以适当配置机加工曲柄销的筒形锻造曲轴。 1.4 以国际单位制或英寸磅单位表示的数值应单独视为标准。每个系统中规定的值可能不是完全相等的；因此，每个系统应独立使用。将两个系统的值合并可能导致不符合标准。 1.5 除非订单规定了适用的“M”规格名称，否则材料应按英寸单位提供。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。

1.1 This is an acceptance specification for the magnetic particle inspection of forged steel crankshafts having main bearing journals or crankpins 4 in. [200 mm] or larger in diameter. 1.2 There are three classes, with acceptance standards of increasing severity: 1.2.1 Class 1. 1.2.2 Class 2 (originally the sole acceptance standard of this specification). 1.2.3 Class 3 (formerly covered in Supplementary Requirement S1 of Specification A456 – 64 (1970)). 1.3 This specification is not intended to cover continuous grain flow crankshafts (see Specification A983/A983M ); however, Specification A986/A986M may be used for this purpose. Note 1: Specification A668/A668M is a product specification which may be used for slab-forged crankshaft forgings that are usually twisted in order to set the crankpin angles, or for barrel forged crankshafts where the crankpins are machined in the appropriate configuration from a cylindrical forging. 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.5 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch units. 1.6 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.