Abstract Unloading compliance method (UC) and normalization method (NM) are two of the most commonly used methods for determining the fracture toughness of steels. Since the NM has been recognized as the most practical method there is a need to evaluate its accuracy against the classic UC method. This paper intends to investigate the factors that affect the agreement between UC and NM, including material mechanical properties, specimen thickness, the ratio of initial crack length to width ( a 0 / W ), specimen configuration, final crack extension, side-groove and the standards used. Both the literature survey and experiments are conducted to produce data for comparison. Based on a thorough analysis of test results, it is found in the paper that the agreement between UC and NM can be greatly affected by material mechanical properties, the ratio of initial crack length to width and the specimen configuration whilst the specimen thickness, the final crack extension and the side-groove only slightly influence the agreement. NM is recommended for specimens with shallow initial crack length, i.e., small a 0 / W . The results presented in the paper can assist engineers and researchers with accurate use of the normalization method for determining fracture toughness of steels.

中文翻译：

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影响卸荷合规法与归一化法一致性的因素

摘要 卸载柔量法（UC）和正火法（NM）是测定钢材断裂韧性最常用的两种方法。由于 NM 已被公认为最实用的方法，因此需要根据经典 UC 方法评估其准确性。本文旨在研究影响UC和NM一致性的因素，包括材料力学性能、试样厚度、初始裂纹长宽比(a 0 / W )、试样配置、最终裂纹扩展、侧槽和使用的标准。进行文献调查和实验以产生用于比较的数据。基于对测试结果的深入分析，论文发现UC和NM之间的一致性受材料力学性能的影响很大，初始裂纹长宽比和试样配置，而试样厚度、最终裂纹扩展和侧槽对一致性的影响很小。NM 推荐用于初始裂纹长度较浅的试样，即小 a 0 / W 。论文中提供的结果可以帮助工程师和研究人员准确使用正火方法来确定钢的断裂韧性。