Abstract The small punch test consists on punching a plane small specimen until it breaks. This technique, born in the 80’s, should be considered when evaluating mechanical properties in situations where materials are in shortage. In recent works, it has been used to estimate the mechanical properties of steels in aggressive environments, where characterizations usually consist on the determination of the threshold stress to avoid subcritical cracking by means of constant loading tests, which is a slow technique, and sometimes presents a considerable dispersion in the results. The standard ASTM F1624 solves these problems, by applying constant loads gradually increased, called loading steps, until the sample fails. In the present work, it is proposed to apply the incremental step loading technique from ASTM F1624 adapted to the Small Punch Test (SPT). As a novel approach, modifications on the steps durations for SPT are proposed according with the sample thickness, allowing to obtain the threshold stress in aggressive environments within a few days, by using at least 3 samples. The proposed methodology is applied to a set of two steels, of medium and high-strength, in hydrogen embrittlement environments under three different levels of cathodic polarization in an acid electrolyte. As a reference, cylindrical tensile specimens were subjected to conventional standard tests in accordance with ASTM F1624. The correlation between the threshold stresses, obtained according to ASTM F1624, and the threshold loads, obtained by the Small Punch proposal, is presented and analyzed. Finally, from the aforementioned correlation, a threshold stress estimation based just on Small Punch tests is proposed.

中文翻译：

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基于增量步加载技术的小冲压试验氢致开裂阈值应力估计

摘要 小冲头试验包括对平面小试样进行冲压直至其断裂。这种技术诞生于 80 年代，在材料短缺的情况下评估机械性能时应考虑使用。在最近的工作中，它已被用于估计钢在侵蚀性环境中的机械性能，其中表征通常包括通过恒定加载试验确定阈值应力以避免亚临界开裂，这是一种缓慢的技术，有时会出现结果的相当大的分散。ASTM F1624 标准解决了这些问题，通过施加逐渐增加的恒定载荷，称为加载步骤，直到样品失效。在目前的工作中，建议应用 ASTM F1624 中适用于小冲压测试 (SPT) 的增量步进加载技术。作为一种新颖的方法，建议根据样品厚度修改 SPT 的步骤持续时间，允许通过使用至少 3 个样品在几天内获得侵蚀性环境中的阈值应力。所提出的方法应用于一组两种钢，中强度和高强度，在酸性电解质中三种不同阴极极化水平下的氢脆环境中。作为参考，圆柱拉伸试样根据 ASTM F1624 进行常规标准测试。呈现并分析了根据 ASTM F1624 获得的阈值应力与通过 Small Punch 提案获得的阈值载荷之间的相关性。最后，