1.1 这些试验方法包括对AISI 304型和304L型（UNS编号分别为S30400和S30403）不锈钢进行电化学再活化（EPR）试验的实验室程序。这些测试方法可以提供一种无损方法来量化304型不锈钢的敏化程度 ( 1. ， 2. ， 3. ) 。 2. 这些EPR试验方法在敏化对晶间腐蚀和晶间应力腐蚀开裂行为的影响研究中得到了广泛认可（见术语 G193 )。EPR技术已成功用于评估其他不锈钢和镍基合金 ( 4. ) ，但在每种情况下使用的测试条件和评估标准都对当前测试方法中引用的条件和评估准则进行了修改。 该标准测试包括两个测试( 1. )试验方法A或单回路，以及( 2. )测试方法B或双环。 1.2 以国际单位制表示的数值应视为标准。SI单位后括号中给出的值仅供参考，不视为标准值。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 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。 ===意义和用途====== 5.1 本试验方法描述了EPR试验方法，用于定量测定AISI 304型和304L型不锈钢的相对敏化程度。EPR试验已被广泛用作在研究敏化对晶间腐蚀和晶间应力腐蚀开裂行为的影响时提供数值敏化水平的手段。该测试方法的结果与其他测试方法相关（例如，实践 A262 和测试方法 G28 )其通常用于评估不锈钢中的敏化作用。 5.2 EPR测试也可用于产品验收、服务评估、监管法规和制造控制，前提是供应商和用户已就适当的验收标准和敏化处理达成一致。 本试验不用于设计目的，因为试验条件以不模拟任何实际使用环境的方式加速腐蚀。 5.3 EPR测试包括测量由沉淀的碳化铬颗粒周围的铬贫化区域的腐蚀产生的电荷量。敏化微观结构中的大多数颗粒位于晶界处。然而，位于晶粒内的离散颗粒（称为晶粒内沉淀物）也将对总测量电荷有贡献。（请参见 图2 .）因此，重要的是在EPR试验后检查合金微观结构，以确定与晶间沉淀物和晶内沉淀物相关的腐蚀位点的相对比例。 晶间侵蚀的位置将类似于实践A中定义的晶界挖沟 A262 。 图2 方法A——单回路EPR测试后的微观结构示意图 注1: 计算 P 一 基于左侧所示的假设。轻度致敏通常会导致晶间腐蚀和点蚀，如右图所示 ( 6. ) 。

1.1 These test methods cover a laboratory procedure for conducting an electrochemical reactivation (EPR) test on AISI Type 304 and 304L (UNS No. S30400 and S30403, respectively) stainless steels. These test methods can provide a nondestructive means of quantifying the degree of sensitization in Type 304 stainless steels ( 1 , 2 , 3 ) . 2 These EPR test methods have found wide acceptance in studies of the effects of sensitization on intergranular corrosion and intergranular stress corrosion cracking behavior (see Terminology G193 ). The EPR technique has been successfully used to evaluate other stainless steels and nickel base alloys ( 4 ) , but the test conditions and evaluation criteria used were modified in each case from those cited in the current test methods. This standard test covers two tests, ( 1 ) Test Method A or Single Loop, and ( 2 ) Test Method B or Double Loop. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 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. ====== Significance And Use ====== 5.1 This test method describes an EPR test method for quantitatively determining the relative degree of sensitization in AISI Type 304 and 304L stainless steels. The EPR test has found wide use as a means to provide a numerical level of sensitization in studies of the effects of sensitization on intergranular corrosion and intergranular stress corrosion cracking behavior. The results of this test method correlate with other test methods (for example, Practices A262 and Test Methods G28 ) that are commonly used to assess sensitization in stainless steels. 5.2 The EPR test can also be used for product acceptance, service evaluation, regulatory statutes, and manufacturing controls providing that both the supplier and user have agreed upon appropriate acceptance criteria and a sensitizing treatment. The test is not intended for design purposes since the test conditions accelerate corrosion in a manner that does not simulate any actual service environment. 5.3 The EPR test involves the measurement of the amount of charge resulting from the corrosion of the chromium-depleted regions surrounding the precipitated chromium carbide particles. Most of these particles in a sensitized microstructure are located at the grain boundaries. However, discrete particles located within grains (referred to as intragranular precipitates) will also contribute to the total measured charge. (See Fig. 2 .) Therefore, it is important to examine the alloy microstructure following an EPR test to determine the relative proportion of corrosion sites associated with intergranular versus intragranular precipitates. Sites of intergranular attack will appear similar to grain boundary ditching as defined in Practice A of Practices A262 . FIG. 2 Schematic Microstructures After EPR Testing for Method A—Single Loop Note 1: The calculation of P a is based on the assumptions illustrated at left. Mild cases of sensitization usually result in a combination of intergranular attack and pitting as illustrated at right ( 6 ) .