Fatigue performance of notched specimens of G20Mn5QT cast steel was investigated experimentally and analytically. Fatigue tests on a total number of 22 semi-circular notched specimens were conducted with the load ratios of − 1 and 0.1. Nominal stress-fatigue life relationship was obtained, and mean stress correction rules were verified for the notched specimens based on the test results. A new strain-based approach, strain field intensity (SNFI) method, was proposed, in which fatigue life of materials is predicted based on the weighted average strain in the fatigue damage region. The fatigue lives of the test specimens were predicted using three strain-based approaches, modified Neuber’s rule, equivalent strain energy density (ESED) method and the proposed SNFI method. The fatigue life prediction by the SNFI method was in very good agreement with the test results, which verified the rationality and applicability of the proposed SNFI method and also the adopted fatigue properties of G20Mn5QT cast steel. Both the modified Neuber’s rule and the ESED method gave conservative prediction of the fatigue life of the notched specimens. The necessity of the 3-dimensional fatigue damage region was also discussed for the proposed SNFI method.

对G20Mn5QT铸钢缺口试样的疲劳性能进行了实验和分析。对总数量为22的半圆形缺口试样进行了疲劳试验，载荷比为-1和0.1。获得名义应力-疲劳寿命关系，并根据测试结果验证缺口试样的平均应力校正规则。提出了一种新的基于应变的方法，即应变场强度（SNFI）方法，其中，基于疲劳损伤区域的加权平均应变来预测材料的疲劳寿命。使用三种基于应变的方法，改进的Neuber规则，等效应变能密度（ESED）方法和建议的SNFI方法，预测了试样的疲劳寿命。SNFI方法的疲劳寿命预测与试验结果吻合得很好，证明了该SNFI方法的合理性和适用性以及G20Mn5QT铸钢所采用的疲劳性能。修正的Neuber规则和ESED方法都可以对缺口试样的疲劳寿命做出保守的预测。对于提出的SNFI方法，还讨论了三维疲劳损伤区域的必要性。