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本文采用普遍适用的近似方法，计算了３１－２５－２型汽轮机９级叶轮在键槽圆角处有径向裂纹 情况下的应力强度因子ＫＩ，并且介绍了叶轮材料３４ＣｒＮｉ３Ｍｏ钢的断裂韧性测试方法及结果。由 大试样测得的ＫＩｃ为４９６ｋｇ／ｍｍ３／２，由小试样测得Ｊ１ｃ后换算成的ＫＩｃ为５０４ｋｇ／ｍｍ３／２±５％， 在ＪＩｃ测定中同时采用单试样法及阻力曲线法。根据叶轮键槽裂纹ＫＩ的计算结果及叶轮材料ＫＩＣ 的测定结果，确定３１－２５－２型汽轮机９级叶轮键槽裂纹的临界长度为６３．５ｍｍ，而类似叶轮飞裂后 断口实测临界裂纹长度为６５～７０ｍｍ，二者符合较好，说明计算与实验结果是可靠的。
In this paper, a general applicable approximation method is used to calculate the stress intensity factor KI of a 9-25 grade turbine with radial cracks at the keyway fillet. The fracture toughness test method of the impeller 34CrNi3Mo steel is also introduced. result. The KIc measured by a large sample was 496 kg / mm3 / 2, and the KIc converted to J1c measured by a small sample was 504 kg / mm3 / 2 ± 5%. In the JIc measurement, a single sample method and a resistance curve law. According to the calculation results of the KI of the impeller keyway crack and the determination result of the KIC of the impeller material, the critical length of the crack of the 9-stage impeller of the 31-25-2 turbine is 63.5mm, and the critical crack length measured by the fractured blade similar to the impeller is 65 ~ 70mm, both in good agreement, indicating that the calculation and experimental results are reliable.