Fatigue cracking criterion of high-strength steels induced by inclusions under high-cycle fatigue
作者机构：Shi-changxu Innovation Center for Advanced Materials Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Materials Science and Engineering University of Science and Technology of China Shenyang 110016 China
出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)
年 卷 期：2023年第154卷第23期
页 面：114-128页
核心收录：
学科分类：08[工学] 0806[工学-冶金工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学]
基 金：financially sup-ported by the National Natural Science Foundation of China(NSFC)(Grant Nos.52001310,52130002,and 51771208) the Strategic Pri-ority Research Program of the Chinese Academy of Sciences(Grant No.XDC04040502) the National Science and Technology Major Project(No.J2019-VI-0019-0134) Outstanding Postgraduate Inno-vative Research Project of Institute of Metal Research,CAS(No.1193002090) KC Wong Education Foundation(No.GJTD-2020-09) Institute of Metal Research Innovation Fund(No.2023-ZD01).
主 题：High-strength steel High-cycle fatigue Critical inclusion size Inclusion types Tensile strength Fracture toughness Fatigue cracking criterion
摘 要：Fatigue properties of high-strength steels become more and more sensitive to inclusions with enhancing the ultimate tensile strength (UTS) because the inclusions often cause a relatively low fatigue strength and a large scatter of fatigue lives. In this work, four S–N curves and more than 200 fatigue fracture morphologies were comprehensively investigated with a special focus on the size and type of inclusions at the fatigue cracking origin in GCr15 steel with a wide strength range by different heat treatments after high-cycle fatigue (HCF). It is found that the percentage of fatigue failure induced by the inclusion including Al2 O3 and TiN gradually increases with increasing the UTS, while the percentage of failure at sample surfaces decreases conversely and the fatigue strength first increases and then decreases. Besides, it is interestingly noted that the inclusion sizes at the cracking origin for TiN are smaller than that for Al2 O3 because the stress concentration factor for TiN is larger than that for Al2 O3 based on the finite element simulation. For the first time, a new fatigue cracking criterion including the isometric inclusion size line in the strength-toughness coordinate system with specific physical meaning was established to reveal the relationship among the UTS, fracture toughness, and the critical inclusion size considering different types of inclusions based on the fracture mechanics. And the critical inclusion size of Al2 O3 is about 1.33 times of TiN. The fatigue cracking criterion could be used to judge whether fatigue fracture occurred at inclusions or not and provides a theoretical basis for controlling the scale of different inclusion types for high-strength steels. Our work may offer a new perspective on the critical inclusion size in terms of the inclusion types, which is of scientific interest and has great merit to industrial metallurgical control for anti-fatigue design.
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