Insights into the stress corrosion cracking of M54 ultra-high-strength steel in the marine environments at varying temperatures by comparison of slow strain rate tensile and crack growth tests

The stress corrosion cracking of M54 steel in marine environments at varying temperatures was investigated. The slow strain rate tensile tests show that increasing the temperature from 5 to 45°C leads to a 71.9 % and 77.4 % decrease in plastic elongation ratio and reduction in area ratio in full immersion environments, while only 7.8 % and 7.9 % in atmospheric environments. The da/dt_II increases from 0.75 nm/s to 5.5 nm/s in atmospheric environments, but first decreases and then increases in full immersion environments. Compared to full immersion environments, the sufficient oxygen supply within the crack in atmospheric environments lowers da/dt_II by 50–80 %.