Abstract:
The present work aims to investigate the role of hydrogen induced blisters cracking on
degradation of tensile and fatigue properties of X65 pipeline steel. Both tensile and fatigue
specimens were electrochemically charged with hydrogen at 20 mA/cm2 for a period of 4 h.
Hydrogen charging resulted in hydrogen induced cracking (HIC) and blister formation
throughout the specimen surface. Nearly all the blisters formed during hydrogen charging
showed blister wall cracking (BWC). Inclusions mixed in Al-Si-O were found to be the
potential sites for HIC and BWC. Slow strain rate tensile (SSRT) test followed by fractographic
analysis confirmed significant hydrogen embrittlement (HE) susceptibility of X65
steel. Short fatigue crack growth framework, on the other hand, specifically highlighted the
role of BWC on accelerated crack growth in the investigated material. Coalescence of
propagating short fatigue crack with BWC resulted in rapid increase in the crack length and
reduced the number of cycles for crack propagation to the equivalent crack length.
