Effect of Prior Austenite Grain Size on the Stress Corrosion Cracking Susceptibility of AISI 4340 Steel

摘要

The stress corrosion cracking susceptibility of tempered AISI 4340 steel in the 0.1N H2SO4 solution was investigated using the compact tension specimens with various notch radii. The crack nucleation at the notch root is determined by the electrical potential method and the acoustic emission method. When the crack initiates, the voltage difference between the notch mouth and the AE energy start to increase. The crack nucleation site is examined by SEM. The crack growth rates are determined by a traveling microscope and the compliance technique. The crack initiation times and crack growth rates depend on grain sizes of materials. These dependencies are successfully explained by a dislocation pile-up model with the hydrogen atom interaction. (Author)