Initiation of fatigue cracks at non-metallic inclusions in large forgings

ABSTRACT A method based on fracture mechanics is required for the prediction of the fatigue load level at which cracks can develop at specific inclusion areas present in large forgings. The results of an investigation of four large forgings containing inclusions of different chemical compositions, morphology, distribution and size indicate that the evaluation of the fatigue cracking behaviour of steel-making inclusions can be performed satisfactorily using linear elastic fracture mechanics principles provided that the inclusions are present in the form of regions containing densely packed particles. On the other hand, the effect of single inclusions not consisting of densely packed regions may be overestimated.