FATIGUE LIFE AND CRACK GROWTH BEHAVIOR IN ANNEALED AND NORMALIZED 0.83% CARBON STEEL

摘要

The variations of fatigue limit and fatigue life of a plain specimen of annealed and normalized 0.83% carbon steel were investigated. This material is used for cutting tools and the original microstructure includes a spherical microstructure. After heat treatment under some conditions, the microstructure changed to a lamellar microstructure. However, the fatigue lives of the plain specimens of this material showed almost the same tendency even after heat treatment under some conditions. In those cases, the initial crack length in the fatigue process is related to the size of the crystal structure and related to the distribution of ferrite. In the present study, the relationship between the distribution of hardness and the fatigue limit was investigated. Also, it was discussed that the fatigue limit of heat-treated 0.83% carbon steel could be evaluated by a relationship in which the parameters are the hardness and initial crack length. Finally, the tendencies of fatigue life of heat-treated 0.83% carbon steel were discussed based on the observations of crack growth behavior.