Changes of Microstructure and Properties of G105 Drill Pipe in H2S Environment

H2S corrosion has become one of the key factors that has impact seriously on the exploration and development of high-sulfur oil and gas. In order to study the change of microstructure and properties of G105 steel drill pipe in H2S environment, different concentrations of H2S (300ppm, 400ppm, 500ppm, 600ppm) were used respectively at room temperature to make corrosion immersion test on the G105 drill pipe, and then tensile test, impact test, hardness test, metallographic analysis, scanning electron microscopy (SEM) observation and EDS spectrum analysis. The results showed that in the range of H2S concentration provided in tests, pipe materials was corroded quite seriously, microstructure changed obviously, comprehensive mechanical properties decreased significantly, and the range decreased first and then increased and decreased again. The type of fracture is classified as the pore ductile fracture, some of them appear prospective cleavage characteristics, and, fracture place exist severe solute partial clustering phenomenon. In addition, high concentration of Sulfur was found in impact fracture surface. The results would provide a reference for our understanding of the corrosion behavior of the drill pipe materials in H2S environment and the development of new anti-corrosion materials drill pipe.