Effect of tempering temperature on very high cycle fatigue properties of high strength steel
Effect of tempering temperature on very high cycle fatigue properties of high strength steel
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发表时间：
2013-05
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通讯作者：
H. Oguma;T. Nakamura
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作者：
H. Oguma;T. Nakamura
为了研究回火温度对超高周疲劳性能的影响，对经433K(640Hv)和573K(543Hv)回火的NiCrMo钢(SNCM439，相当于AISI4340钢)进行了单轴拉压疲劳试验。在104-105周次范围内的断口位于试件表面，而在105-108周次范围内的断口为亚表面断口。表面萌生失效的疲劳极限与传统的σW0≈1.6Hv公式吻合较好。然而，在较硬的条件下，亚表面裂纹萌生区域的疲劳极限较低。扫描电子显微镜分析表明，断裂起因的夹杂物类型取决于回火温度。这种依赖关系可能是在很高的循环疲劳范围内，硬度和疲劳强度之间存在异常关系的原因。
To investigate the effect of tempering temperature on the very high cycle fatigue properties, uniaxial tension-compression fatigue tests of Ni-Cr-Mo steel (SNCM439, corresponding to AISI 4340 steel) which had been tempered, either at 433K (640Hv) or 573K (543Hv) were carried out. The fracture origins in 104 - 105 cycle range located at the specimen surface, whereas in the 105 - 108 cycle range the fracture origins were sub-surface. The fatigue limits for the surfaceinitiated failures were in good agreement with the conventional expression σw0 ≈ 1.6·Hv. However, in the the fatigue limit in the sub-surface crack-initiation range was lower for the harder condition. SEM examination showed that the type of inclusion at the failure origin depended upon the tempering temperature. This dependency may be the cause of the unusual relation between hardness and fatigue strength in the very high cycle fatigue range.