L51491 Effect of Temperature on Stress-Corrosion Cracking of Pre-Cracked Line-Pipe Steel

Research conducted in the Stress-Corrosion-Cracking Phase of the NG-18 program has demonstrated that a number of factors influence the rate of stress-corrosion cracking. These factors are the susceptibility of the steel, the stress level, and loading amplitude, the chemical environment in contact with the steel surface, the electrochemical potential established on the steel surface, and the temperature of the steel/environment system. The temperature, as was pointed out by Fessler et al., has an effect on crack growth rate, the width of the potential range where stress-corrosion cracking occurs, and the range of strain rates within which stress-corrosion cracking is possible. It was shown that each of these effects can act to decrease the susceptibility of line pipe steel to stress-corrosion cracking.

Although the beneficial effects of lowering the temperature on the stress-corrosion cracking behavior of line pipe steels in carbonate/bicarbonate solutions was shown, no data are available concerning the effect on initiation of stress-corrosion cracks. The objective of this study was to determine the effect of temperature on the KISCC and the stress-corrosion crack velocity of line pipe steels. This study was initiated to determine whether lowering the temperature of the environment could prevent a stress-corrosion crack from initiating or could stop existing and propagating cracks.