1.1 本实施例描述了在沸腾氯化镁溶液中进行应力腐蚀开裂试验的程序。尽管可以使用各种浓度的氯化镁进行该测试，但该程序涵盖了保持在155.0°C±1.0°C（311.0°F±1.8°F）恒定沸腾温度的测试溶液。氯化镁水溶液在一个大气压下的沸点作为浓度的函数如图所示 图1 . 2 本文还描述了能够将溶液浓度和温度长时间保持在规定限度内的建议测试设备。 3 1.2 沸腾氯化镁试验适用于锻造、铸造和焊接不锈钢及相关合金。它是一种检测成分、热处理、表面光洁度、微观结构和应力对这些材料氯化物应力腐蚀开裂敏感性的影响的方法。4 1.3 本实践主要涉及测试溶液，其可用于各种应力腐蚀测试样品、表面光洁度和施加应力的方法。 1.4 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。 见第节 7 特定的安全预防措施。 1.5 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》中确立的国际公认的标准化原则制定的。======意义和用途====== 5.1 对于大多数应用，这种环境提供了一种对不锈钢和相关合金在含水氯化物环境中的应力腐蚀开裂敏感性的相对程度进行排序的加速方法。通常在热氯化物使用中提供可接受阻力的材料可能在该测试中破裂。该试验可能与多硫酸或腐蚀性环境中的应力腐蚀开裂无关。 5.2 在可能的情况下，在沸腾氯化镁（155.0°C（311.0°F））中的抗应力腐蚀开裂性应与相关材料的使用阻力相关联。然而，这种相关性可能并不总是可能的。 5.3 沸腾的氯化镁也可能导致许多不锈钢合金点蚀。这导致将应力腐蚀失效与由腐蚀减少的净横截面引起的机械故障相混淆的可能性。当使用小横截面样品、高施加应力水平、长暴露周期、耐应力腐蚀合金或其组合时，这种危险特别大。建议仔细检查，以正确诊断故障原因。

1.1 This practice describes a procedure for conducting stress-corrosion cracking tests in a boiling magnesium chloride solution. Although this test may be performed using various concentrations of magnesium chloride, this procedure covers a test solution held at a constant boiling temperature of 155.0 °C ± 1.0 °C (311.0 °F ± 1.8 °F). The boiling points of aqueous magnesium chloride solutions at one atmosphere pressure as a function of concentration are shown graphically in Fig. 1 . 2 A suggested test apparatus capable of maintaining solution concentration and temperature within the prescribed limits for extended periods of time is also described herein. 3 1.2 The boiling magnesium chloride test is applicable to wrought, cast, and welded stainless steels and related alloys. It is a method for detecting the effects of composition, heat treatment, surface finish, microstructure, and stress on the susceptibility of these materials to chloride stress corrosion cracking. 4 1.3 This practice is concerned primarily with the test solution, which may be used with a variety of stress corrosion test specimens, surface finishes, and methods of applying stress. 1.4 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. See Section 7 for specific safety precautions. 1.5 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 For most applications, this environment provides an accelerated method of ranking the relative degree of stress-corrosion cracking susceptibility for stainless steels and related alloys in aqueous chloride-containing environments. Materials that normally provide acceptable resistance in hot chloride service may crack in this test. The test may not be relevant to stress-corrosion cracking in polythionic acid or caustic environments. 5.2 Resistance to stress-corrosion cracking in boiling magnesium chloride (155.0 °C (311.0 °F)) should, where possible, be correlated to resistance in service for the materials of interest. However, such correlations may not always be possible. 5.3 Boiling magnesium chloride may also cause pitting of many stainless alloys. This leads to the possibility of confusing stress-corrosion failures with mechanical failures induced by corrosion-reduced net cross sections. This danger is particularly great when small cross section samples, high applied stress levels, long exposure periods, stress-corrosion resistant alloys, or a combination thereof are being used. Careful examination is recommended for correct diagnosis of the cause of failure.