1.1 本规范 2. 包括用于压缩机、膨胀机、泵、阀门和其他主要用于低温服务的承压零件的D-2M型1级和2级奥氏体球墨铸铁。 1.2 这些等级的奥氏体球墨铸铁的特点是其石墨基本呈球状，不含鳞片石墨。它们基本上不含碳化物，并含有足够的合金含量，以产生稳定的奥氏体基体，直至−423°F[−252℃（液态氢）。 1.3 以国际单位制或英寸表示的数值- 磅单位应单独视为标准单位。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.3.1 在文本中，国际单位显示在括号中。 1.4 以下预防性警告仅适用于试验方法部分第节 11 ，本规范: 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。

1.1 This specification 2 covers austenitic ductile iron, Type D-2M, Classes 1 and 2, for compressors, expanders, pumps, valves, and other pressure-containing parts intended primarily for low-temperature service. 1.2 These grades of austenitic ductile iron are characterized by having their graphite substantially in a spheroidal form and free of flake graphite. They are essentially free of carbides and contain sufficient alloy content to produce a stable austenitic matrix down to −423°F [−252°C] (liquid hydrogen). 1.3 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. 1.3.1 Within the text, the SI units are shown in brackets. 1.4 The following precautionary caveat pertains only to the test methods portion, Section 11 , of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.