摘要
高速重载轴承圈的淬火裂纹失效是制约机械装备服役可靠性的瓶颈问题,阐明其失效机制对优化热处理工艺和保障关键零部件性能至关重要。本研究以20CrMnTi钢制轴承圈淬火开裂为研究对象,通过宏微观断口表征、金相检测、化学检测等多种手段揭示了裂纹萌生与扩展的多尺度机制。实验结果表明:裂纹源于距表面2~3 mm位置,在原始裂纹中心存在直径81μm的氧化铝夹杂物。后续在热处理过程中原始裂纹沿环向扩展,断口呈现沿晶+准解理混合脆性断裂特征,且扩展区无塑性变形痕迹,证实失效模式为由淬火应力主导的原始裂纹扩展。结合有限元多场耦合仿真进一步建立了温度场-相变场-应力场交互模型,定量揭示了裂纹尖端的I型应力强度因子(K_(IC))的动态演化规律:当初始裂纹长度超过1.84 mm时,淬火拉应力使K_(IC)在淬火开始后14 s达到临界值(128 MPa·m^(1/2)),裂纹发生失稳扩展;此时裂尖区域温度、马氏体相变程度与实验观测结果一致。基于断裂力学判据与工程保守性原则,建议生产中对含内部裂纹(长度超过1.8 mm)的20CrMnTi工件规避淬火处理。
The quenching crack failure of high-speed and heavy-duty bearing ring is the bottleneck problem limiting the service reliability of machinery equipment.Therefore,it is crucial to clarify its failure mechanism for optimizing heat treatment processes and ensuring the performance of key components.This study focused on the cracking phenomenon of 20CrMnTi steel bearing rings during quenching.Through various methods such as macroscopic and microscopic fracture characterization,metallographic examination,and chemical analysis,the multi-scale mechanism of crack initiation and propagation was revealed.The experimental results showed that the cracks initiated from the position with distance of 2-3 mm to surface,and there were aluminum oxide inclusions with diameter of 81μm at the center of original cracks.The original cracks extended along the hoop in subsequent heat treatment process,and the fracture showed the characteristics of intergranular-quasi-cleavage hybrid brittle fracture.Moreover,there was no plastic deformation trace in the extension area,which proved that the failure mode was the original crack extension dominated by quenching stress.By combining with finite element multi-field coupling simulation,a temperature field-phase transformation field-stress field interactive model was further established.The dynamic evolution law of I-type stress intensity factor(KIC)of crack tip was quantitatively reveled:when the length of original crack exceeded 1.84 mm,the quenching tensile stress made KIC reach the critical value(128 MPa·m1/2)after 14 s of quenching,and the unstable propagation of cracks occurred.At this time,the temperature of crack tip area and the phase transition degree of martensite were consistent with the observation results in experiments.According to fracture mechanics criterion and engineering conservatism principle,it was suggested that the quenching treatment should be avoided in production for 20CrMnTi pieces with internal cracks(the length more than 1.8 mm).
作者
赵睿
潘志强
钟振前
高群
ZHAO Rui;PAN Zhiqiang;ZHONG Zhenqian;GAO Qun(Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;Power(BEIJING)Engineering Supervision Co.,Ltd.,Beijing 100080,China;NCS Testing Technology Co.,Ltd.,Beijing 100081,China)
出处
《物理测试》
2025年第4期1-6,共6页
Physics Examination and Testing
基金
国家电投集团风电门框多缺陷协同修复与残余应力调控技术研究项目(2025BJC031226)。
