A Study on Initial Crack-Nucleating Condition in Delayed Fracture

Abstract

In the preceding report, the effects of hydrogen upon various characteristics of steel were found by performing the static bending test and delayed fracture test on the specimens in which hydrogen was introduced by acid dipping.
In this report, the initial crack-nucleating condition in delayed fracture has been obtained based on the plastic solution of A.P. Green et al. for a sharply V notched specimen and the experimental results of the preceding report. And also the maximum stress to nucleate a crack when hydrogen is introduced has been obtained by using the calculation and the diagrams.
Furthermore, the static bending test and delayed fracture test were performed on the high strength hexagon bolts in order to ascertain whether this result can be applied in practice. And it has been found that the crack-nucleating stress obtained is applicable.