Microstructure and Properties of Steels Used for High-Strength Casings and Tubings Manufacturing

摘要

Along with high level strength and cold resistance casing and tubings used to construct oil and gasreserves with higher hydrogen sulfide (H_2S) content should have high corrosion resistance.Medium carbon Cr-Mo steels are basically used for casing and tubes manufacture. Such twosteels with various Mo and V content are observed in this paper.Continuous cooling transformation (CCT) diagrams were plotted for steels. Undercooled austenitewith more stability was discovered in steel with higher Mo and V content.After quenching and tempering at temperature range from 680 to 720 °C “more-alloyed” steel hashigher level of yield-strength but it’s plasticity is somewhat lower than that of another one. Dynamictests data showed high enough cold resistance of both steels at minus 60 °C regardless temperingtemperature.Sulfide stress corrosion cracking (SCC) tests (NACE TM0177 Method A) at 0.85 of yieldingstrength showed that with increasing of Mo and V content in steel leads to significant growth ofcorrosion resistance.