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Crack initiation mechanism of M50 bearing steel under high cycle fatigue
International Journal of Fatigue ( IF 6 ) Pub Date : 2023-02-18 , DOI: 10.1016/j.ijfatigue.2023.107587
Jun Guo, Aimin Zhao, Maosheng Yang

The fatigue properties of M50 bearing steel under high cycle fatigue were studied by rotating bending fatigue test at room temperature. The fatigue cracks of M50 bearing steel were primarily nucleated at MgO-Al2O3 inclusions and MC/M2C primary carbides. The voids were initiated through inclusion debonding from the matrix and primary carbide cracking under cyclic loading. Small cracks were initiated on the void along the direction perpendicular to the tensile stress. Small cracks propagated at a speed of 8.81 × 10-10 m/cycle with hysteresis in the fine granular area (FGA). When the stress intensity factor range for the subsurface defect was lower than the stress intensity factor range threshold for M50 steel, the initiation stage of fatigue crack was composed of crack nucleation caused by defects and fatigue process in FGA. The fatigue cracks propagated at the fish-eye area (FiE) when the stress intensity factor range at the FGA front exceeded ΔKth. There was a stress concentration at the inclusion-matrix interface or the primary carbide-matrix interface during a long-term cyclic loading which resulted in the nucleation of fatigue cracks. A fatigue crack nucleation model was established based on the true stress at the defect, size of the defect, and number of cycles. A fatigue life model was constructed based on fatigue crack nucleation and fatigue crack propagation processes.



中文翻译:

M50轴承钢高周疲劳裂纹萌生机理

采用室温旋转弯曲疲劳试验研究了M50轴承钢在高周疲劳下的疲劳性能。M50轴承钢的疲劳裂纹主要在MgO-Al 2 O 3夹杂物和MC/M 2 C一次碳化物处形核。空洞是通过基体中的夹杂物脱粘和循环载荷下的初级碳化物开裂而产生的。沿着垂直于拉应力的方向在空隙上开始出现小裂纹。小裂纹以 8.81 × 10 -10的速度扩展m/cycle 在精细颗粒区域 (FGA) 中具有滞后现象。当亚表面缺陷的应力强度因子范围低于M50钢的应力强度因子范围阈值时,疲劳裂纹的萌生阶段由缺陷引起的裂纹形核和FGA中的疲劳过程组成。当 FGA 前沿的应力强度因子范围超过 Δ K th时,疲劳裂纹在鱼眼区(FiE)扩展. 在长期循环加载过程中,夹杂物-基体界面或初生碳化物-基体界面存在应力集中,导致疲劳裂纹形核。基于缺陷处的真实应力、缺陷尺寸和循环次数建立了疲劳裂纹形核模型。基于疲劳裂纹形核和疲劳裂纹扩展过程构建了疲劳寿命模型。

更新日期:2023-02-18
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