Hydrogen Uptake and Embrittlement Susceptibility of Ferrite-Pearlite Pipeline Steels

Two ferrite-pearlite steels API 5L X52 and ASTM A106 Grade B with different pearlite phase morphologies were studied. It is assumed that the interphases of the cementite and ferrite lamellae within the pearlite colonies as well as non-metallic inclusions (NMIs) trap effectively hydrogen resulting in specific hydrogen uptake, diffusion transport and embrittlement of the ferrite-pearlite steels. Hydrogen was introduced into the specimens by electrochemical hydrogen charging and analysed by thermal desorption spectroscopy. Hydrogen effects were studied for the materials after spheroidizing heat treatment of the cementite phase and after pre-straining. The aim of the study is to investigate the influence of the pearlite phase morphology on hydrogen uptake, trapping and embrittlement susceptibility of ferrite-pearlite steels.