1.1本试验方法涵盖了通过监测电镀或涂层过程（如规范F 1137和F 1941中所述）尽可能防止紧固件内部氢脆（IHE）的程序。与鉴定每批电镀或涂层的紧固件相比，定期使用最少数量的试样对该过程进行定量监测。与每批紧固件的统计抽样分析相比，趋势分析用于确保质量。该试验方法包括机械试验，用于评估和控制电镀或涂层过程中各种氢源可能产生的IHE的可能性。 1.2本试验方法包括在用作见证的标准试样上进行的机械试验，以评估和控制电镀或涂层过程中各种氢源可能产生的IHE的可能性。 1.3本试验方法仅限于评估因加工（IHE）而非环境暴露（EHE，见试验方法F 1624）引起的氢致脆化。 1.4本试验方法不用于测量钢对IHE或EHE的相对敏感性。 1.5本试验方法仅限于评估用于电镀或涂层含铁紧固件的工艺。 1.6本试验方法使用符合试验方法F 519 1e型的缺口方棒试样，但增加半径以适应更大范围镀层和涂层的沉积。关于测试方法F 519测试的背景，请参阅出版物ASTM STP 543和ASTM STP 962。应力集中系数为a K t = 3.1 0.2. 通过恒定外加阴极电位来控制氢含量，证明了灵敏度。残余氢的灵敏度和基线将通过在空气中对裸金属试样进行测试来确定。 1.7应证明每批试样对IHE的敏感性。用热处理至50至52 HRC硬度范围的AISI E4340钢制成的试样，用于产生“最坏情况”条件，并最大限度地提高对IHE的敏感性。 1.8该试验是一种加速（24小时）试验方法，用于测量氢应力开裂阈值，并用于量化试样中的残余氢量。根据试验方法F 1624，通过使用增量载荷和位移控制下的保持时间，对试样进行持续载荷和慢应变率试验，以加速方式测量阈值应力。 1.9在本试验方法中，使用弯曲代替拉伸，因为其在缺口钢筋中产生的最大局部极限载荷拉应力高达根据试验方法E 8测量的屈服强度的2.3倍。安装时无意中受到弯曲的紧固件可能会达到该最大局部拉应力。 1.10以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 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。 ====意义和用途====== 本试验方法建立了一种方法，通过在生产操作（如表面处理、预处理和电镀或涂层）期间保持严格控制，尽可能验证在制造过程中防止钢紧固件中的IHE。其旨在用作新的或修改的电镀或涂层工艺的鉴定测试，以及用于控制电镀或涂层工艺的定期检查审计。 通过该试验，可以将紧固件在空气中拉伸至规定的最小拉伸载荷，几乎不可能因加工而在空气中发生延时断裂。如果残余氢的量不足以在最坏情况下诱发试样开裂或断裂，则可以得出结论，如果工艺保持在控制状态，则在此期间加工的所有批次紧固件将不会有足够的残余氢从加工中诱发紧固件在空气应力下的氢脆，不变且稳定。 如果经认证的样品对IHE具有敏感性，并用紧固件处理，则有一个阈值 ≥ 增量阶跃载荷缺口弯曲断裂应力的75%，NFS（B） F 1624 假设在此期间以相同方式处理的所有紧固件也将通过任何持续负载IHE测试。 图1 0.4W缺口方棒弯曲试样的尺寸要求

1.1 This test method covers a procedure to prevent, to the extent possible, internal hydrogen embrittlement (IHE) of fasteners by monitoring the plating or coating process, such as those described in Specifications F 1137 and F 1941. The process is quantitatively monitored on a periodic basis with a minimum number of specimens as compared to qualifying each lot of fasteners being plated or coated. Trend analysis is used to ensure quality as compared to statistical sampling analysis of each lot of fasteners. This test method consists of a mechanical test for the evaluation and control of the potential for IHE that may arise from various sources of hydrogen in a plating or coating process. 1.2 This test method consists of a mechanical test, conducted on a standard specimen used as a witness, for the evaluation and control of the potential for IHE that may arise from various sources of hydrogen in a plating or coating process. 1.3 This test method is limited to evaluating hydrogen induced embrittlement due only to processing (IHE) and not due to environmental exposure (EHE, see Test Method F 1624). 1.4 This test method is not intended to measure the relative susceptibility of steels to either IHE or EHE. 1.5 This test method is limited to evaluating processes used for plating or coating ferrous fasteners. 1.6 This test method uses a notched square bar specimen that conforms to Test Method F 519, Type 1e, except that the radius is increased to accommodate the deposition of a larger range of platings and coatings. For the background on Test Method F 519 testing, see publications ASTM STP 543 and ASTM STP 962. The stress concentration factor is at a K t = 3.1 0.2. The sensitivity is demonstrated with a constant imposed cathodic potential to control the amount of hydrogen. Both the sensitivity and the baseline for residual hydrogen will be established with tests on bare metal specimens in air. 1.7 The sensitivity of each lot of specimens to IHE shall be demonstrated. A specimen made of AISI E4340 steel heat treated to a hardness range of 50 to 52 HRC is used to produce a "worst case" condition and maximize sensitivity to IHE. 1.8 The test is an accelerated (24 h) test method to measure the threshold for hydrogen stress cracking, and is used to quantify the amount of residual hydrogen in the specimen. The specimen undergoes sustained load and slow strain rate testing by using incremental loads and hold times under displacement control to measure a threshold stress in an accelerated manner in accordance with Test Method F 1624. 1.9 In this test method, bending is used instead of tension because it produces the maximum local limit load tensile stress in a notched bar of up to 2.3 times the yield strength as measured in accordance with Test Method E 8. A fastener that is unintentionally exposed to bending on installation may attain this maximum local tensile stress. 1.10 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 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. ====== Significance And Use ====== This test method establishes a means to verify the prevention, to the extent possible, of IHE in steel fasteners during manufacture by maintaining strict controls during production operations such as surface preparation, pretreatments, and plating or coating. It is intended to be used as a qualification test for new or revised plating or coating processes and as a periodic inspection audit for the control of a plating or coating process. Passing this test allows fasteners to be stressed in tension to the minimum specified tensile load in air with almost no possibility of time delayed fracture in air as a result of IHE from processing. If the amount of residual hydrogen is not sufficient to induce cracking or fracture in the specimen under worst case conditions, then it can be concluded that all of the lots of fasteners processed during that period will not have sufficient residual hydrogen from processing to induce hydrogen embrittlement of the fasteners under stress in air if the process remains in control, unchanged and stable. If certified specimens with demonstrated sensitivity to IHE, processed with the fasteners, have a threshold ≥ 75 % of the incremental step load notched bend fracture stress, NFS(B) F 1624 , it is assumed that all fasteners processed the same way during the period will also pass any sustained load IHE test. FIG. 1 Dimensional Requirements for a 0.4W-Notched Square Bar Bend Specimen