L80钢在CO2/H2S腐蚀环境中的力学特性

目的：研究L80钢在CO2/H2S环境中的力学特性。方法利用微机控制慢应变速率拉伸试验机，对特定腐蚀条件下的L80钢试样进行拉伸实验，分析各因素对L80钢力学特性的影响变化规律。结果在CO2/H2S环境中，随着含水率的增加，L80钢的屈服强度、抗拉强度、延伸率均下降，L80钢拉伸曲线出现劣化。随预拉应力的增大，L80钢的屈服强度变化不明显，而抗拉强度和延伸率降低，当预拉应力超过0.8σs时，L80钢的腐蚀速率显著增加，表现出较强的应力腐蚀敏感性；随着H2S分压的增加， L80钢的力学性能发生劣化，表现出氢脆敏感性，而受CO2分压的影响不明显；温度升高导致L80钢的拉伸曲线出现了轻度劣化，延伸率和屈服区宽度小幅降低，但抗拉强度变化不大。结论 L80钢在CO2/H2S环境中的力学特性受温度、CO2分压影响程度小。含水率和预拉应力的增大降低了L80钢的力学韧性，预拉应力的存在使L80腐蚀速率加快，缩短了耐腐蚀寿命。L80钢的力学性能对于H2S分压较对CO2分压更为敏感，试样的断裂是机械拉力和应力腐蚀共同作用的结果。

Mechanical Properties of L80 Steel in CO2/H2S Environment

ABSTRACT:Objective To study the mechanical properties of L80 steel in CO2 / H2S environment.Methods Slow strain rate tensile testing machine was used to conduct tensile tests on L80 samples in specific corrosion conditions, and the influence rules of each factor on the mechanical properties of L80 steel were analyzed.Results In CO2/H2S environment, with the increase of water cut, the tensile curve of L80 tubing steel appeared to degrade, the yield strength, tensile strength, and elongation all de-creased; With the increase of tensile stress, the yield strength of L80 steel had no significant change, the tensile strength and elongation decreased, and the corrosion rate significantly changed when the tensile stress exceeded 0.8σs, which showed strong stress corrosion sensitivity; With the increase of H2S partial pressure, the mechanical properties of L80 steel decreased, show-ing relatively strong hydrogen embrittlement sensitivity, but influence of CO2 partial pressure on L80 steel was not obvious; Tensile curve of L80 steel underwent mild degradation with the increase of temperature, the elongation and yield zone width re-duced with a small amplitude, but the tensile strength just changed a little.ConclusionTemperature and CO2had a small effect on the mechanical properties of L80 steel; The increase of water cut and tensile stress reduced the mechanical toughness of L80 steel, accelerated the corrosion rate of L80 steel, and shortened the anticorrosion longevity of L80 steel; Mechanical properties of L80 steel were more sensitive to H2S than CO2, and sample fracture was the result of the combination of machine tensile and stress corrosion.