研究了一种2 000 MPa级中碳高强度弹簧钢的疲劳破坏行为。升降法得出实验钢的旋转弯曲疲劳极限σ-1为810 MPa，此值明显高于传统弹簧钢；这主要得益于实验钢具有良好的强度和塑韧性配合及均匀细小的奥氏体晶粒。用SEM对疲劳断口的分析表明，实验钢的疲劳破坏均起源于试样表层的非金属夹杂物，其主要成分为含Ti和V的碳氮化物，平均尺寸为(50±10)μm，且呈“鱼眼”断裂。相对于试样心部的夹杂物，表层夹杂物对实验钢的疲劳性能的危害性更大。
Fatigue fracture behaviour of a mediumcarbon 2 000 MPa level high strength spring steel was investigated. The rotatingbending fatigue limit of the tested steel is 810 MPa, which is obviously superior to that of conventional spring steels. This is mainly because the tested steel has fine austenite grains and good combination of strength, toughness and ductility. SEM examination of fracture surface shows that fatigue cracks are all initiated by nonmetallic inclusions on the subsurface with an average size of 50±10 μm and therefore fisheye type fractures are developed. Composition of these inclusions is mainly Ti and/or V carbnitride. Nonmetallic inclusions on the subsurface of specimen do great harm to its fatigue property than that in the centre of specimen.
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