1.1 本试验方法包括通过金属板材料的拉伸试验确定应变硬化指数，金属板材料的塑性流动行为服从引言中给出的功率曲线。 附注1: 单个功率曲线可能无法令人满意地拟合屈服和颈缩之间的整个应力-应变曲线。如果是这种情况，可以获得多于一个的应变硬化指数值 ( 2 ) 通过协议使用该测试方法。 1.2 该测试方法专门适用于厚度至少为0.005英寸的金属板材料。（0.13 mm）但不大于0.25 in。（6.4毫米）。该方法已经成功地并且可以通过协议应用于其他形式和厚度 1.3 以英寸-磅单位表示的值应被视为标准值。括号中给出的值是对SI单位的数学转换，仅供参考，不被视为标准。附注2: 应变硬化指数的值， n 、无单位且独立于其厘定所用单位 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。 1.5 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 该试验方法可用于估计单轴拉伸试验中颈缩开始时的应变 ( 1 ) 在实践中，它为评价类似金属体系的相对拉伸成形性提供了经验参数。应变硬化指数也是材料由于塑性变形而强度增加的量度。 5.2 应变硬化指数可以在整个塑性应力-应变曲线或产品说明书中规定的应力-应变曲线的任何部分上确定。 附注4: 确定应变硬化指数通常采用10%-20%的工程应变区间， n 、可成形低碳钢产品 5.3 本试验方法不适用于表现出不连续行为的真实应力-真实应变曲线的任何部分；然而，该方法可以通过商定的曲线平滑技术来应用。附注5: 例如，低碳钢、铝或其他合金的应力-应变曲线中表现出屈服点和吕德斯带伸长、孪晶或波特文-勒夏特列效应(PLC)的那些部分可以被表征为表现不连续。 附注6: 在使用曲线平滑技术时应小心，因为它们可能会影响 n -价值。 5.4 该试验方法适用于测定金属板材在颈缩开始前塑性区的拉伸应力-应变响应。 5.5 The n -值可能随所用的位移速率或应变速率而变化，这取决于金属和测试温度。

1.1 This test method covers the determination of a strain-hardening exponent by tension testing of metallic sheet materials for which plastic-flow behavior obeys the power curve given in the introduction. Note 1: A single power curve may not be a satisfactory fit to the entire stress-strain curve between yield and necking. If such is the case, more than one value of the strain-hardening exponent may be obtained ( 2 ) by agreement using this test method. 1.2 This test method is specifically for metallic sheet materials with thicknesses of at least 0.005 in. (0.13 mm) but not greater than 0.25 in. (6.4 mm). The method has successfully been and may be applied to other forms and thicknesses by agreement 1.3 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. Note 2: The value of the strain-hardening exponent, n , has no units and is independent of the units used in its determination 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. 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 This test method is useful for estimating the strain at the onset of necking in a uniaxial tension test ( 1 ) . Practically, it provides an empirical parameter for appraising the relative stretch formability of similar metallic systems. The strain-hardening exponent is also a measure of the increase in strength of a material due to plastic deformation. 5.2 The strain-hardening exponent may be determined over the entire plastic stress-strain curve or any portion(s) of the stress-strain curve specified in a product specification. Note 4: The engineering strain interval 10 % – 20 % is commonly used for determining the strain-hardening exponent, n , of formable low-carbon steel products 5.3 This test method is not intended to apply to any portion of the true stress versus true strain curve that exhibits discontinuous behavior; however, the method may be applied by curve-smoothing techniques as agreed upon. Note 5: For example, those portions of the stress-strain curves for mild steel, aluminum, or other alloys that exhibit yield point and Lüders band elongation, twinning, or Portevin–Le Chatelier effect (PLC) may be characterized as behaving discontinuously. Note 6: Caution should be observed in the use of curve-smoothing techniques as they may affect the n -value. 5.4 This test method is suitable for determining the tensile stress-strain response of metallic sheet materials in the plastic region prior to the onset of necking. 5.5 The n -value may vary with the displacement rate or strain rate used, depending on the metal and test temperature.