论文部分内容阅读
对12CrNi3A 钢在冲击和非冲击疲劳栽荷下的过载裂纹扩展延迟效应研究表明:过载对随后裂纹扩展的影响不仅取决于过载力作用下的裂尖塑变,还取决于随后基载力作用下的裂尖塑变.过载对随后裂纹扩展的影响存在两个互为矛盾的方面:一是裂尖塑变损伤促进裂纹扩展;另一是产生残余压应力场和闭合效应延缓裂纹扩展,两方面共同作用结果才能最终决定对随后裂纹扩展的影响.实验结果还表明,冲击疲劳载荷下的过载延迟效应与过载力的冲击速度有关,相同条件下,冲击疲劳载荷下的延迟期 Nd 高于非冲击疲劳载荷;各种因素对过载延迟的影响程度在两种载荷制度下不相同.
The study on the effect of overload crack propagation delay on 12CrNi3A steel under impact and non-impact fatigue load shows that the influence of overload on the subsequent crack propagation depends not only on the plastic deformation of the crack tip under the overload force but also on the subsequent load-bearing force Of the crack tip plastic deformation.The impact of the overload on the subsequent crack growth there are two contradictory aspects: one is the crack tip plastic damage to promote crack growth; the other is to produce residual compressive stress field and closure effect to delay the crack growth, two aspects The results show that the effect of overload delay under impact fatigue load is related to the impact velocity of overload force under the same conditions. Under the same conditions, the delay period Nd under impact fatigue load is higher than that of non-impact Fatigue load; the influence of various factors on the overload delay is different under the two load systems.