Mechanical Properties and CO₂ Corrosion Behavior of Q125 Grade Oil Tube Steel Used in Deep Oil Well

Abstract:

A type of Q125 grade high-strength low carbide oil tube steel was designed and researched. The strengthening mechanism of the steel was analyzed by SEM and TEM, and the CO2 corrosion behavior of the steel was simulated by high-temperature and high-pressure autoclave. The result show: the size of original austenite grain, packet and block are about 10-15μm, 2μm and 200nm, respectively, so the strength of the steel matched toughness well. The precipitate of (Nb,Ti)(C,N) whose size is about 60nm can restrain coarsening of the original austenite grain through pitting austenite grain boundary; The precipitate of (Nb,Ti)C and nanometer sized precipitate of NbC can be an effective barrier for dislocation motion, so that has great contributions to improve the strength of the steel. The average and pitting corrosion rate increased first and then dropped down with the increasing of temperature. There is a maximum of average and pitting corrosion rate at 90°C; Simultaneously, when the temperature is 90°C, there is a biggest difference between average corrosion rate and pitting corrosion rate.

• Periodical: Advanced Materials Research (Volumes 524-527)
• Pages: 1471-1479
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.524-527.1471
• Online since: May 2012
• Authors: Di Tang, Li Dong Wang, Hui Bin Wu, Jin Ming Liang
• Keywords: CO₂ Corrosion, Nanometer Sized Precipitate, Pitting Corrosion Rate

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