Hydrogen-Induced Cracking Assessment in Pipeline Steels Through Permeation and Crystallographic Texture Measurements, By Mohammad Ali Mohtadi Bonab

Research

Title	Hydrogen-Induced Cracking Assessment in Pipeline Steels Through Permeation and Crystallographic Texture Measurements
Type	Article
Keywords	crystallographic texture, electron backscatter diffraction (EBSD), energy dispersive spectroscopy (EDS), hydrogen charging, hydrogen permeation
Researchers	Mohammad Ali Mohtadi Bonab، Rahim Karim dadashi، Mostafa Eskandari، Jerzy A. Szpunar

Abstract

Electrochemical hydrogen charging and permeation techniques were used to characterize hydrogen distribution, trapping, and diffusion in X60 and X60 sour service (X60SS) pipeline steels. The results obtained contribute to better understanding of hydrogen-induced cracking (HIC). SEM observations illustrated that all HIC cracks were formed at the center of cross section in the X60 steel after 3-h hydrogen charging and length of cracks increased with charging time. No HIC cracks were recorded at the cross section of X60SS steel after the same charging for different durations. Hydrogen permeation tests showed that the density of reversible hydrogen traps was lower at the center of cross section in the X60SS steel compared to the X60 one, and this is considered as one of the main reasons for high resistance of X60SS steel to HIC. EBSD orientation imaging results proved that the accumulation of <111>||ND-oriented grains at the center of the cross section in the X60SS steel was high. This is also considered as another reason for higher resistance of this steel to HIC. Finally, the center segregation zone with higher hardness value in the X60 steel was more pronounced than in the X60SS steel which made the X60 steel susceptible to HIC cracking.