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本文研究了16Mn钢的疲劳裂缝扩展行为,结合晶粒尺寸和微观断裂机理从变形约束的角度对门槛值△k_(th)和Ⅱ_a→Ⅱ_b转折的力学条件进行了分析,并对疲劳裂缝扩展参数的工程意义进行了讨论。研究确定△k_(th)随铁素体晶粒尺寸的增大而提高。但晶粒粗化会降低疲劳裂纹扩展抗力,增加在较高应力强度水平的扩展速度。研究指出,对于以△k_(th)作为主要设计指标的情况,对材料晶粒度要求可以适当放宽,在疲劳失效分析工作中应用疲劳条纹间距估计应力强度水平和宏观裂纹扩展速度应取审慎态度。
In this paper, the fatigue crack propagation behavior of 16Mn steel was studied. The mechanical conditions of △ k_ (th) and Ⅱ_a → Ⅱ_b transitions were analyzed from the perspective of deformation constraints in combination with the grain size and microscopic fracture mechanism. The fatigue crack propagation parameters The engineering significance is discussed. The results show that △ k_ (th) increases with the increase of ferrite grain size. However, grain coarsening will reduce fatigue crack propagation resistance and increase the rate of expansion at higher stress levels. It is pointed out that for the case of Δk th (th) as the main design index, the grain size of the material should be suitably relaxed. It is prudent to estimate the stress intensity level and the macroscopic crack propagation rate in fatigue failure analysis .