氢对酸性气田低合金钢氢渗透及应力腐蚀行为的影响

Effect of Hydrogen on Hydrogen Permeation and Stress Corrosion Behavior of Low Alloy Steel in Acid Gas Field

摘要:

采用电化学氢渗透、慢应变速率拉伸（SSRT）实验和体视显微镜、SEM观察断口形貌的方法进行探究80SS低合金油管钢在饱和CO2模拟采出水环境中，氢对氢渗透和应力腐蚀开裂行为的影响。结果表明，随着溶液H+浓度增大，酸性的增加，氢渗透参数i^∞、D和"C" _"0" ^"H" 均会增大，有助于氢原子的扩散行为；在拉应力和氢原子的协同作用下，与空拉对比，80SS低合金钢的断裂时间减少了近50%，发生了由韧性断裂到脆性断裂的变化，随着溶液氢浓度的增大，对钢材引起的力学损伤增强，应力腐蚀敏感性增大；80SS钢在含饱和CO2采出水介质中拉伸时，预充氢前后的指数Iδ由3.16增大到8.49，预充氢加大了试样的应力腐蚀开裂敏感性；在含1% HAc的饱和CO2采出水中拉伸时，预充氢前的微观形貌呈现出河流花样，出现准解理断裂特征，而预充氢后的80SS钢纤维区分布有不连续裂纹和小孔状结构，与预充氢前的相比，预充氢增加了钢的塑性性能，降低了钢材的应力腐蚀开裂敏感性。

Abstract:

In this study, the effects of hydrogen concentration on hydrogen permeation and stress corrosion cracking behavior in 80SS low-alloy tubing steels in a saturated CO2 simulated produced water environment was explored by electrochemical hydrogen permeation, slow strain rate tension and stereo microscope, SEM methods. The results show that the acidity and the hydrogen permeation parameters i^∞, D and C_0^H were both increasing with the raise of the concentration of H+, which contributes to the diffusion behavior of hydrogen atoms. Since the synergistic effect of tensile stress and hydrogen atom, the fracture time of 80SS low alloy steel is reduced by nearly 50% compared with the tensile in air, and the change is occurred to ductile fracture to brittle fracture. As the hydrogen concentration of the solution increases, the mechanical damage of the steel and the stress corrosion sensitivity strengthen. Before and after pre-charged hydrogen the index Iδ changed from 3.16 to 8.49 when 80SS steel is stretched in a medium containing saturated CO2. Pre-charged hydrogen promoted the stress corrosion cracking sensitivity of the sample. When stretched in saturated CO2 produced water containing 1% HAc, the microscopic morphology before pre-charged hydrogen showed a river pattern with quasi-cleavage fracture characteristics. Discontinuous cracks and small pores are distributed with fiber area of 80SS steel of the pre-charged hydrogen. Compared with before pre-charged sample, pre-charged hydrogen improved the plastic properties of the steel and reduced the stress corrosion cracking sensitivity of the steel.