1.1 本试验方法包括断裂韧性的测定（ K Ic 并且任选地 K 内容 ）使用厚度为1.6 mm（0.063 in.）或更大的疲劳预裂纹试样，在主要线性弹性平面应变条件下的金属材料 2 缓慢地或在特殊（选择性）情况下快速地承受增加的裂纹位移力。测试设备、样品配置和实验程序的详细信息见附录。概述了使用实验数据计算断裂韧性值的两个程序: 1.1.1 The K Ic 本试验标准正文中描述了试验程序，是本试验方法试验和结果报告程序的强制性部分。The K Ic 试验程序基于高达试样宽度2%的裂纹扩展。这可能导致取决于试样尺寸的断裂韧性阻力曲线上升，较大的试样产生较高的断裂韧性结果。 1.1.2 The K 内容 测试程序描述于 附录X1 并且是该测试方法的可选部分。The K 内容 测试程序基于0.5 mm的固定裂纹扩展量，结果， K 内容 对样品尺寸的敏感性低于 K Ic 这种对尺寸不太敏感的断裂韧性， K 内容 在整个测试方法中，称为尺寸不敏感。 附录X1 包含用于重新解释作为本试验方法一部分记录的力-位移试验记录以计算附加断裂韧性值的可选程序， K 内容 . 附注1: 厚度小于1.6毫米（0.063英寸）的材料的平面应变断裂韧性试验。）足够脆（见 7.1 ）可以使用其他类型的标本制作 ( 1 ) . 3 对于这种薄材料，没有标准的测试方法。 1.2 本试验方法分为两部分。第一部分给出了测试的一般建议和要求，并包括对 K Ic 测试程序。第二部分由附录组成，给出了位移计和加载夹具设计的具体信息、单个试样配置的特殊要求以及疲劳预裂的详细程序。提供了额外的附件，给出了铍和快速力测试的具体程序，以及 K 内容 测试程序，该程序为作为 K Ic 测试程序。 1.3 所有样本配置共有的一般信息和要求: 部分 参考文献 2 术语 3 应力强度因子 3.1.1 平面应变断裂韧性 3.1.2 裂纹平面取向 3.1.4 试验方法总结 4 意义和用途 5 意义 5.1 注意事项 5.1.1– 5.1.5 实际应用 5.2 仪器（另见 1.4 ) 6 张力机 6.1 疲劳机 6.2 装载夹具 6.3 位移计，测量 6.4 样本大小、配置和制备（另见 1.5 ) 7 样本量估计 7.1 标准和替代样本配置 7.2 疲劳裂纹起始缺口 7.3.1 疲劳预裂（另见 1.6 ) 7.3.2 裂纹延伸超出起动机缺口 7.3.2.2 一般程序 8 样本测量 厚度 8.2.1 宽度 8.2.2 裂纹尺寸 8.2.3 裂纹平面角 8.2.4 标本检测 加载方法 8.3 装载率 8.4 试验记录 8.5 结果的计算和解释 9 试验记录分析 9.1 P 米 a x /P Q 有效性要求 9.1.3 样本量有效性要求 9.1.4 报告 10 精密度和偏差 11 1.4 与试验设备相关的具体要求: 双悬臂位移计 附件A1 测试夹具 附件A2 弯曲试样加载夹具 Annex A2.1 紧凑型试样加载U形夹 Annex A2.2 1.5 与单个样本配置相关的具体要求: 弯曲试样 SE(B) 附件A3 致密试样 C(T) 附件A4 圆盘形致密试样 直流(T) 附件A5 弧形拉伸试样 A(T) 附件A6 弧形弯曲试样 A(B) Annex A7 1.6 与特殊试验程序相关的具体要求:疲劳预裂 K Ic 和 K 内容 标本 附件A8 热压铍测试 Annex A9 快速力测试 附件A10 测定 K 内容 附录X1 1.7 以SI单位表示的值应被视为标准。括号中给出的值仅供参考。 1.8 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。 1.9 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 物业 K Ic 通过该试验方法测定的材料表征了在基本上线弹性应力和严重拉伸约束下，在存在尖锐裂纹的中性环境中材料的抗断裂性，使得 (1) 裂纹前沿附近的应力状态接近三拉伸平面应变，并且 (2) 与裂纹尺寸、试样厚度和裂纹前的韧带相比，裂纹尖端塑性区较小。 5.1.1 价值的变化 K Ic 可以预期在试样比例的允许范围内， A/W 和 W/B . K Ic 也可能随着韧带尺寸的增加而增加。然而，尽管有这些变化， K Ic 被认为代表了在环境中以及在测试的速度和温度下断裂韧性的下限值（对于2%的表观裂纹扩展）。5.1.2 从解理断裂失效的试样中可以获得更低和更高度可变的断裂韧性值；例如，在韧脆过渡区或更低的温度下测试的铁素体钢的样品。因解理而失效的试样也更有可能表现出温预应力效应，其中在高于试验温度的温度下预开裂可以人为地增加测量的断裂韧性 ( 2 ) 本试验方法不适用于解理断裂。相反，请用户参考测试方法 E1921 和 E1820 其适用于解理断裂并含有防止温预应力的安全措施。同样，当试样失效伴有明显的塑性变形时，即使试样尺寸在产品尺寸限制范围内最大化，也不应使用该试验方法。测试方法中给出了测试弹塑性材料的指南 E1820 . 5.1.3 的价值 K Ic 通过该试验方法获得的结果可用于估计在使用中的材料的失效应力和裂纹尺寸之间的关系，其中将预期上述高约束条件。关于根据线弹性断裂力学开发该试验方法的基础的背景信息可在参考文献中找到 ( 1 ) 和 ( 3 ) . 5.1.4 循环力会导致裂纹扩展 K 我 值小于 K Ic 循环或持续力下的裂纹扩展（如应力腐蚀裂纹或蠕变裂纹扩展）会受到温度和环境的影响。因此，当 K Ic 应用于服务部件的设计时，应考虑实验室测试和现场条件之间的差异。5.1.5 平面应变断裂韧性试验是不寻常的，因为不能预先保证有效的 K Ic 将在特定测试中确定。因此，必须遵守本试验方法规定的有效性标准。 5.1.6 残余应力会将偏差引入指示的 K Q 和 K Ic 价值确定。对于从热处理或以其他方式未消除应力的坯料、从焊接件、从复杂锻造产品、快速凝固铸件、增材制造产品或从具有有意引起的残余应力的产品中取出的样品，该效果可能特别显著。此外，当试样从主体产品中取出并加工时，残余应力将重新分布。残余应力影响的大小 K Q 和 K Ic 在测试样品中可能与原始或最终加工产品中的有很大不同。此外，由于每个样品中不同残余应力的影响，全尺寸产品中裂纹的行为可能无法从样品上测量的断裂韧性中预测。残余应力的指示包括试样加工过程中的变形、取决于试样构型的结果以及不规则的疲劳预裂纹扩展（裂纹前曲率过大或平面外扩展）。指南 B909 为完全应力消除不可行的铝合金产品的平面应变断裂韧性测试提供补充指南。指南 B909 包括用于识别残余应力何时可能显著影响测试结果的附加指南，以及用于在测试期间最小化残余应力影响的方法。5.2 该测试方法可用于以下目的: 5.2.1 在研究和开发中，以定量的方式确定冶金变量（如成分或热处理）或制造操作（如焊接或成型）对新材料或现有材料断裂韧性的影响，对使用性能具有重要意义。 5.2.2 在使用评估中，确定材料对特定应用的适用性，该应用规定了应力条件，并且可以有把握地确定最大缺陷尺寸。 5.2.3 对于验收和制造质量控制的规范，但只有在有合理的基础规定最低 K Ic 值，然后只有当产品的尺寸足以提供有效所需尺寸的样品时 K Ic 决心。的规格 K Ic 与特定应用相关的值应表明，已经对部件进行了与预期载荷和环境相关的断裂控制研究，以及与在使用前和随后在预期寿命期间应用的裂纹检测程序的灵敏度和可靠性相关的断裂控制研究。

1.1 This test method covers the determination of fracture toughness ( K Ic and optionally K Isi ) of metallic materials under predominantly linear-elastic, plane-strain conditions using fatigue precracked specimens having a thickness of 1.6 mm (0.063 in.) or greater 2 subjected to slowly, or in special (elective) cases rapidly, increasing crack-displacement force. Details of test apparatus, specimen configuration, and experimental procedure are given in the annexes. Two procedures are outlined for using the experimental data to calculate fracture toughness values: 1.1.1 The K Ic test procedure is described in the main body of this test standard and is a mandatory part of the testing and results reporting procedure for this test method. The K Ic test procedure is based on crack growth of up to 2 % percent of the specimen width. This can lead to a specimen size dependent rising fracture toughness resistance curve, with larger specimens producing higher fracture toughness results. 1.1.2 The K Isi test procedure is described in Appendix X1 and is an optional part of this test method. The K Isi test procedure is based on a fixed amount of crack extension of 0.5 mm, and as a result, K Isi is less sensitive to specimen size than K Ic . This less size-sensitive fracture toughness, K Isi , is called size-insensitive throughout this test method. Appendix X1 contains an optional procedure for reinterpreting the force-displacement test record recorded as part of this test method to calculate the additional fracture toughness value, K Isi . Note 1: Plane-strain fracture toughness tests of materials thinner than 1.6 mm (0.063 in.) that are sufficiently brittle (see 7.1 ) can be made using other types of specimens ( 1 ) . 3 There is no standard test method for such thin materials. 1.2 This test method is divided into two parts. The first part gives general recommendations and requirements for testing and includes specific requirements for the K Ic test procedure. The second part consists of Annexes that give specific information on displacement gage and loading fixture design, special requirements for individual specimen configurations, and detailed procedures for fatigue precracking. Additional annexes are provided that give specific procedures for beryllium and rapid-force testing, and the K Isi test procedure, which provides an optional additional analysis procedure for the test data collected as part of the K Ic test procedure. 1.3 General information and requirements common to all specimen configurations: Section Referenced Documents 2 Terminology 3 Stress-Intensity Factor 3.1.1 Plane-Strain Fracture Toughness 3.1.2 Crack Plane Orientation 3.1.4 Summary of Test Method 4 Significance and Use 5 Significance 5.1 Precautions 5.1.1 – 5.1.5 Practical Applications 5.2 Apparatus (see also 1.4 ) 6 Tension Machine 6.1 Fatigue Machine 6.2 Loading Fixtures 6.3 Displacement Gage, Measurement 6.4 Specimen Size, Configurations, and Preparation (see also 1.5 ) 7 Specimen Size Estimates 7.1 Standard and Alternative Specimen Configurations 7.2 Fatigue Crack Starter Notches 7.3.1 Fatigue Precracking (see also 1.6 ) 7.3.2 Crack Extension Beyond Starter Notch 7.3.2.2 General Procedure 8 Specimen Measurements Thickness 8.2.1 Width 8.2.2 Crack Size 8.2.3 Crack Plane Angle 8.2.4 Specimen Testing Loading Methods 8.3 Loading Rate 8.4 Test Record 8.5 Calculation and Interpretation of Results 9 Test Record Analysis 9.1 P m a x /P Q Validity Requirement 9.1.3 Specimen Size Validity Requirements 9.1.4 Reporting 10 Precision and Bias 11 1.4 Specific requirements related to test apparatus: Double-Cantilever Displacement Gage Annex A1 Testing Fixtures Annex A2 Bend Specimen Loading Fixture Annex A2.1 Compact Specimen Loading Clevis Annex A2.2 1.5 Specific requirements related to individual specimen configurations: Bend Specimen SE(B) Annex A3 Compact Specimen C(T) Annex A4 Disk-Shaped Compact Specimen DC(T) Annex A5 Arc-Shaped Tension Specimen A(T) Annex A6 Arc-Shaped Bend Specimen A(B) Annex A7 1.6 Specific requirements related to special test procedures: Fatigue Precracking K Ic and K Isi Specimens Annex A8 Hot-Pressed Beryllium Testing Annex A9 Rapid-Force Testing Annex A10 Determination of K Isi Appendix X1 1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.8 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. 1.9 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 The property K Ic determined by this test method characterizes the resistance of a material to fracture in a neutral environment in the presence of a sharp crack under essentially linear-elastic stress and severe tensile constraint, such that (1) the state of stress near the crack front approaches tritensile plane strain, and (2) the crack-tip plastic zone is small compared to the crack size, specimen thickness, and ligament ahead of the crack. 5.1.1 Variation in the value of K Ic can be expected within the allowable range of specimen proportions, a/W and W/B . K Ic may also be expected to rise with increasing ligament size. Notwithstanding these variations, however, K Ic is believed to represent a lower limiting value of fracture toughness (for 2 % apparent crack extension) in the environment and at the speed and temperature of the test. 5.1.2 Lower and more highly variable values of fracture toughness can be obtained from specimens that fail by cleavage fracture; for example, specimens of ferritic steels tested at temperatures in the ductile-to-brittle transition region or below. Specimens failing by cleavage are also more likely to exhibit warm prestressing effects, where precracking at a temperature higher than the test temperature can artificially increase the fracture toughness measured ( 2 ) . The present test method is not intended for cleavage fracture. Instead, the user is referred to Test Method E1921 and E1820 which are applicable to cleavage fracture and contain safeguards against warm prestressing. Likewise this test method should not be used when specimen failure is accompanied by appreciable plastic deformation even after the specimen size has been maximized within product dimensional constraints. Guidance on testing elastic-plastic materials is given in Test Method E1820 . 5.1.3 The value of K Ic obtained by this test method may be used to estimate the relation between failure stress and crack size for a material in service wherein the conditions of high constraint described above would be expected. Background information concerning the basis for development of this test method in terms of linear elastic fracture mechanics may be found in Refs ( 1 ) and ( 3 ) . 5.1.4 Cyclic forces can cause crack extension at K I values less than K Ic . Crack extension under cyclic or sustained forces (as by stress corrosion cracking or creep crack growth) can be influenced by temperature and environment. Therefore, when K Ic is applied to the design of service components, differences between laboratory test and field conditions shall be considered. 5.1.5 Plane-strain fracture toughness testing is unusual in that there can be no advance assurance that a valid K Ic will be determined in a particular test. Therefore, compliance with the specified validity criteria of this test method is essential. 5.1.6 Residual stresses can introduce bias into the indicated K Q and K Ic value determinations. The effect can be especially significant for specimens removed from as-heat treated or otherwise non-stress relieved stock, from weldments, from complex wrought products, rapidly-solidified castings, additively-manufactured products or from products with intentionally induced residual stresses. In addition, residual stresses will redistribute when the specimen is extracted from the host product and machined. The magnitude of residual stress influence on K Q and K Ic in the test specimen may be quite different from that in the original or finish machined product. In addition, the behavior of cracks in the full-sized product may not be predictable from the fracture toughness measured on the specimen because of the influence of the different residual stresses in each. Indications of residual stress include distortion during specimen machining, results that are specimen configuration dependent, and irregular fatigue precrack growth (either excessive crack front curvature or out-of-plane growth). Guide B909 provides supplementary guidelines for plane strain fracture toughness testing of aluminum alloy products for which complete stress relief is not practicable. Guide B909 includes additional guidelines for recognizing when residual stresses may be significantly biasing test results, and methods for minimizing the effects of residual stress during testing. 5.2 This test method can serve the following purposes: 5.2.1 In research and development, to establish in quantitative terms significant to service performance, the effects of metallurgical variables such as composition or heat treatment, or of fabricating operations such as welding or forming, on the fracture toughness of new or existing materials. 5.2.2 In service evaluation, to establish the suitability of a material for a specific application for which the stress conditions are prescribed and for which maximum flaw sizes can be established with confidence. 5.2.3 For specifications of acceptance and manufacturing quality control, but only when there is a sound basis for specifying minimum K Ic values, and then only if the dimensions of the product are sufficient to provide specimens of the size required for valid K Ic determination. The specification of K Ic values in relation to a particular application should signify that a fracture control study has been conducted for the component in relation to the expected loading and environment, and in relation to the sensitivity and reliability of the crack detection procedures that are to be applied prior to service and subsequently during the anticipated life.