Effects of (Ti, Mo)C precipitation on the microstructure, impact toughness, and sulfide stress corrosion cracking resistance of linepipe steels

Abstract

There is a growing need to develop high-performance linepipes owing to the accelerated resource depletion attributable to the increasing interest in mining in extreme environments. (Ti, Mo)C precipitation can help secure the strength, low-temperature toughness, and sulfide stress corrosion cracking (SSCC) resistance required for linepipes. In this study, high-strength low-alloy (HSLA) steels with (Ti, Mo)C precipitation and without Ti and Mo were fabricated to analyze the effects of (Ti, Mo)C precipitation on the microstructure, impact toughness, and SSCC resistance of linepipes. The (Ti, Mo)C precipitation behavior varied and caused differences in the phase fraction, grain size, and dislocation density. Such differences in the microstructure improved the strength and low-temperature impact toughness. The SSCC resistance was significantly improved. In conclusion, (Ti, Mo)C precipitation has the potential to improve the properties required for fabricating linepipes.

Keywords

• Linepipe steel
• (Ti
• Mo)C precipitation
• Sulfide stress corrosion cracking resistance
• Microstructure