CO_2压力对金属腐蚀产物膜形貌结构的影响

EFFECT OF CO_2 PARTIAL PRESSURE ON THE MORPHOLOGY OF CORROSION METALLIC PRODUCT SCALES

在高温高压静态釜中对 3种油套钢N80、P110和J5 5的CO2 腐蚀进行了模拟腐蚀试验 .通过扫描电子显微镜 (SEM)对比分析了腐蚀产物膜的厚度和表面平均晶粒大小随CO2 压力的变化规律 .结果显示 ,在试验条件下 ,3种材料所得到的腐蚀产物膜的纵向形貌为双层结构 ,其膜厚随着CO2 分压变化情况比较相近 ,在CO2 分压为6 89MPa时 ,膜厚均达到最大 ,在超临界压力以上急剧减小 ;膜表面平均晶粒大小随CO2 压力的变化都出现了两个峰值和一个低谷 ,并且在超临界压力以上随着压力增加均急剧减小 ,而峰值或低谷所对应的CO2 压力和晶粒大小 ,3种材料存在明显的差异 .

Simulated autoclave is employed to study the corrosion process of three kinds of oil well steels in CO 2 environment with varying CO 2 partial pressure.The effect of the CO 2 partial pressure on the average scale thickness and crystal grain size of the scales is studied by using scanning electron microscope(SEM).The results show that,the cross-section of the corrosive product scales of the three kinds of steels are doublelayers in the structures,the variation of average scale thickness for the three kinds of steels with CO 2 partial pressure is in the similar manner,of which the maximum average scale thickness appears at the CO 2 partial pressure about 6.89MPa and then decreased rapidly.The variations of the average crystal grain size with CO 2 partial pressure for the three steels exhibit two peaks and a valley in between; however the CO 2 partial pressures corresponding to the peaks and valley and crystal grain sizes for different materials vary,and crystal grain sizes of the three steels with CO 2 partial pressure decreased quickly beyond the peaks.