Grain boundary microchemistry and stress-corrosion failure of mild steel

Abstract

A common cause of failure of large metallic components is stress corrosion, often in subtle combination with fatigue. In the case of carbon steel as used in pipelines, the problem of understanding the cause of variations in susceptibility to intergranular stress corrosion between steel batches of apparently similar origin, history and operating conditions has been researched for many years. We report here the results of investigations including Auger electron spectroscopy which show that the source of variable behaviour is probably the differences in the micro-chemical content of grain boundary paths, differences which may easily exist between one batch or another of apparently similar steel.