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本文对中碳合金结构钢经循环热处理晶粒细化的效应,同时再施以滚压形变后的表层残余应力、旋转弯曲疲劳性能、断口形貌,微观组织亚结构,进行了试验研究,并与正常热处理的试验结果作了比较。试验结果表明:40CrMo钢的缺口疲劳强度(r=1mm)σ_(-1H)由原来的50～55kgf/mm~2提高到100～115kgf/mm~2的水平,疲劳试样的缺口经滚压形变强化后,钢的缺口疲劳强度σ_(-1H)可以达到或超过光滑试样的疲劳强度σ_(-1o)这一结果的工程意义在于,零件几何形状的等强度设计必然不可避免地带来台阶、圆角过渡和缺口,各部位的材料疲劳强度并非是等强度的,在使用中往往就会在这些薄弱的部分产生疲劳断裂。如对这些部分采用局部形变强化的方法,造成有利的残余压应力,对提高局部有效承载能力,是极为有效的。
In this paper, the effect of cyclic heat treatment on grain refinement of medium-carbon alloyed structural steel was studied, and the surface residual stress, rotational bending fatigue property, fracture morphology and microstructure substructure after rolling deformation were applied. Compared with the results of normal heat treatment test. The results show that the notched fatigue strength (r = 1mm) σ_ (- 1H) of 40CrMo steel increases from 50 ~ 55kgf / mm ~ 2 to 100 ~ 115kgf / mm ~ 2. After the deformation strengthening, the notched fatigue strength σ _ (- 1H) of steel can reach or exceed the fatigue strength of the smooth specimen σ _ (- 1o). The engineering significance of the result of this result is that the equal strength design of the part geometry inevitably brings about the step , Fillet transition and notches, the fatigue strength of various parts of the material is not equal strength, often in the use of these weak parts will produce fatigue fracture. Such as the use of these parts of the local deformation strengthening method, resulting in favorable residual compressive stress, to improve the local effective carrying capacity, is extremely effective.