There is a close relationship between the fatigue strength and the tensile strength of the material under certain conditions. Therefore, under certain conditions, all alloy elements that can improve the tensile strength can improve the fatigue strength of the material. In comparison, carbon is the most important factor affecting the strength of the material. However, some impurity elements that form inclusions in steel have an adverse effect on fatigue strength.
2 Effects of heat treatment and microstructure
Different heat treatment states will obtain different microstructures. Therefore, the effect of heat treatment on fatigue strength is essentially the effect of microstructure. Materials of the same composition, due to different heat treatments, can obtain the same static strength, but due to different structures, the fatigue strength can vary within a considerable range.
At the same strength level, the fatigue strength of flaky pearlite is significantly lower than that of granular pearlite. The same is granular pearlite, the finer the cementite particles, the higher the fatigue strength.
The influence of microstructure on the fatigue properties of materials is not only related to the mechanical properties of various structures, but also to the grain size and the distribution characteristics of the structures in the composite structure. Grain refinement increases the fatigue strength of the material.
