The following propounds a simple way to predict the appearance of cracks. When plane carbon steel reaches the yield point, Lueder's line appear. When stress exceeds yield stress the Lueder's lines change into an orange peel texture. These phenomena are in all cases visible. Therefore it is possible to use the visible change in the appearance of the Lueder's lines that accompanies the increase in loading as a simple device to predict the appearance of cracks. Since the visible surface conditions are used as the predictor, it is unnecessary to use any special instrument. All one has to do is to make the surface that is to be observed flat and smooth. It is an extremely simple technique. Observation was made of the change of state on the flat, smooth surface of a basic material undergoing cyclic loading. Investigation was made of the relation between Stretcher Strains, or the orange peel texture, and the S-N diagram. It was possible to apprehend the process by which the state of the flat, smooth surface changed from the moment that the Stretcher Strains developed until the appearance of cracks. The utilization of the results of this experiment render a concrete example of the possibility of predicting the appearance of cracks by visual observation of stretcher strains. One may consider the use of Lueder's lines or the orange peel texture to be a reliable method for experimental stress analysis.
"Prediction of crack generation", Proc. SPIE 2947, Nondestructive Evaluation of Utilities and Pipelines, (14 November 1996); doi: 10.1117/12.259177; https://doi.org/10.1117/12.259177