Strength Evaluation of Gray Cast Iron on the Basis of Quantitative Analysis of Graphite Shape

Abstract

For gray cast iron, it is not easy to perform the non-destructive estimation of material strength and failure analysis, such as quantitative evaluation and estimation of failure mode.
The authors applied an image processing technique to measure the graphite size and the area ratio of graphite on the fracture surface, and tried to correlate those with the material strength and failure mode based on the fact that graphite is the key factor for the fracture of cast iron.
The followings were obtained in this report. The tensile strength had a correlation to the maximum length of graphite which was obtained by statistical treatment. This relationship can be used for the non-destructive estimation of tensile strength. Moreover, the area ratio of graphite on the fatigue fracture surface depended on the applied stress level.