On the sulfide stress cracking resistance of a 125 ksi grade high-strength low-alloyed steel for oil country tubular goods

Abstract

Excellent sulfide stress cracking (SSC) resistance was achieved in a 125 ksi grade high-strength low-alloyed steel with increased C content and Cu alloying. Results showed that increased C content allowed tempering at higher temperature, obtaining low dislocation density without decreasing strength. Moreover, Cu alloying refined martensite blocks and inhibited dislocation annihilation, but hardly influenced the precipitation of Cr-rich carbides. The decrease in dislocation density was the main reason for improving SSC resistance, and sufficient precipitation of Cr-rich carbides came in second. Despite Cu alloying failing to improve the SSC resistance, it increased the yield strength without sacrificing SSC resistance.