Study On Hydrogen-induced Cleavage Fracture Of X80 Pipeline Steel

The behaviors of X80 pipeline steel hydrogen-induced cracking(HIC) was investigated by electrochemistry hydrogen charging and slow strain rate tensile testing. The diffuse behaviors of hydrogen and the mechanical properties of X80 pipeline steel under different loading rates and different current densities was studied.The results shows:X80 pipeline steel after electrochemistry hydrogen charging in 0.5mol/LH2SO4 solution, with the charging time and current densities was increased, the hydrogen concentration increased. The hydrogen concentration in a linear relationship with current densities:Under dynamic hydrogen charging, with the loading rates was decreased or current densities was increased, the plastic and strength of X80 pipeline steel was decreased. The fracture strength of X80 pipeline steel decreased linearly with logarithm of the hydrogen concentration:The hydrogen-induced fracture had the appearance of dimples and cleavage facets, with the increase of hydrogen content, dimples became smaller and lighter. Fracture surface exhibits typical cleavage morphology.The criticality hydrogen concentration on crack tip increased linear with square root of the current densities: The fracture strength decreased linear with square root of the criticality hydrogen concentration:...