Tensile Property of L80 Steel in Air at 25-350 ℃ and Its Corrosion Behavior in Simulated Casing Service Conditions at 150-350 ℃

In this article, the tensile fracture behavior of L80 steel in air at 25-350^oC and its high-tem-perature and high-pressure corrosion behavior in CO₂ /H₂ S in an artificial formation water at 150-350^oC are investigated by means of mass loss measurement, scanning electron microscopy, X-ray photoelec-tron spectroscopy. The results suggest that the yield strength and tensile strength of L80 both appear to severe decline with the increasing temperature, while the decay of the former is significantly greater than that of the latter. Meanwhile, the tensile fracture mechanism of L80 steel changes from microporous aggregation with shear tearing at room temperature to a dominant microporous aggregation at high temper-atures. The corrosion rate increases significantly with the increasing temperature, and the higher the tem-perature, the faster the increase rate. The bilayer structure of the corrosion products and their crystal morphology are markedly affected by temperature, and the percentage of FeS in the inner layer and the com-pactness of FeCO₃ of the outer layer both increase with the increasing temperature. The results of the study may provide a reference for the evaluation of the adaptability of L80 oil casing for service in ex-treme conditions.