30Cr2Ni4MoV转子钢Ⅱ型裂纹的疲劳扩展行为

Fatigue Propagation Behavior of Mode Ⅱ Crack of 30Cr2Ni4MoV Rotor Steel

材料疲劳裂纹扩展(Fatigue crack propagation,FCP)速率是表征材料抗疲劳破坏的重要力学性能指标,是对核反应堆工程、化工、航空、航天、高铁等关键工程进行结构完整性评价的重要依据。采用Arcan试样对30Cr2Ni4MoV转子钢的Ⅱ型裂纹疲劳扩展行为进行研究,结合已有裂纹扩展方向预测准则对Ⅱ型裂纹疲劳扩展方向进行预测,结果表明,最大周向应力准则可以较好地预测Ⅱ型裂纹疲劳扩展方向。采用紧凑拉伸(Compact tension,CT)试样获取30Cr2Ni4MoV转子钢的I型裂纹疲劳扩展速率,对比I型裂纹和Ⅱ型裂纹的疲劳扩展试验获得的FCP速率与J积分范围关系趋势,二者较为接近。针对30Cr2Ni4MoV转子钢,依据Arcan试样获得的Ⅱ型裂纹疲劳扩展速率试验结果可用于结构裂纹扩展剩余寿命的预测。

The fatigue crack propagation(FCP) rate is important index of mechanical properties for characterizing the fatigue failure of materials, they are the important basis for structural integrity assessment of key projects such as nuclear reactor engineering, chemical engineering, aeronautics and astronautics, and high-speed railway, etc. The Arcan specimens are used to study the FCP behavior of mode Ⅱ crack of 30Cr2Ni4MoV rotor steel. The fatigue propagation direction of mode Ⅱ crack is predicted by the existing crack propagation criterion. The results show that the maximum circumferential stress criterion can predict the fatigue propagation direction of mode Ⅱ crack. The compact tension(CT) specimens are used to study the FCP behavior of mode I crack of 30Cr2Ni4MoV rotor steel. The relationship between the FCP rates and the range of J integral obtained from the fatigue growth tests of mode I crack and mode Ⅱ crack are compared, and they are very close. Therefore, for the 30Cr2Ni4MoV rotor steel, the results of the mode Ⅱ crack fatigue growth rates obtained according to the Arcan specimens tests can be used to predict the remaining life of the cracked structures.