拉伸超载对超高强度钢A-100冲击疲劳性能的影响

Effect of Tensile Overloading on Impact Fatigue Properties of Ultra-high Strength Steel A-100

研究了A-100钢单边缺口三点弯曲试样经拉伸超载处理后,冲击疲劳性能的变化。在室温下测得拉伸超载处理前后,冲击能量-冲击疲劳寿命曲线,并对冲击疲劳断口进行微观分析。结果表明:拉伸超载可延长A-100钢的冲击疲劳裂纹起始寿命而对裂纹扩展寿命无影响;试样超载后裂纹源区微观形貌发生变化,缺口根部残余压应力的存在是造成这些变化的主要原因。

The changes on impact fatigue properties for three-point bend specimens of ultra-high strength steel A-100 after tensile overloading were investigated. Impact energies-crack initial life curve and impact energies-fi＇acture life curve were measured at room temperature before and after overloading. The fatigue fracture morphologies were also analyzed. The results show that under certain conditions, the tensile overloading increases the impact fatigue crack initiation life, but has no significant effects on the impact fatigue propagation life. Compared with the morphologies of un-overloading specimens, some changes were found in the crack source area of overloading specimens. The compressive residual stress induced by overloading at the notch root of specimen is the main mechanism of the change of crack morphology.