微觀組織和合金成分對CO2腐蝕行為的影響規律

Effect of Microstructure and Composition on CO2 Corrosion

對API-X65、1Cr-X65和16Mn三種材料在四種典型的高温高壓介質環境和工藝條件中的CO2腐蝕行為進行了研究，其結果顯示，16Mn表現出非常優越的耐局部腐蝕能力。在四種狀態中，均未發生局部腐蝕。1Cr-X65的抗局部部腐蝕能力比API-X65也有顯著提高，前者的局部腐蝕只在兩種狀態出現，而後者在三種狀態均出現局部腐蝕。局部腐蝕的統計分析顯示，1Cr-X65的局部腐蝕深度比API-X65淺的多。三種材料無論是全面腐蝕還是局部腐蝕，其耐蝕性的排序均是：16Mn>1Cr-X65>API-X65。微觀分析顯示，16Mn的優良抗CO2腐蝕能力可能來源於16Mn中肥粒體的電位相對較負，雪明碳體中的滲碳體電位相對較正，產生微電池效應，導致肥粒體優先溶解而形成腐蝕產物膜與金屬基體介面呈週期性間隔凸起，這種膜／基體介面犬牙交錯的機構對腐蝕產物膜具有“釘錨效應”，導致這種材料腐蝕產物膜與基體具有優良的附著力，從而抗流體剪切的能力比較高，在靜態和動態條件下形成腐蝕產物膜的剪切強度均高於API-X65。

The corrosion behavior of API-X65, 1Cr-X65, l6Mn in four typical CO2-containing solutions and conditions were investigated in this paper. Weight loss results indicated that 16Mn exhibited excellent resistance to localized corrosion and no localized corrosion was observed in all the four conditions. The resistance to localized corrosion of 1Cr-X65 obviously was improved compare to API-X65. Statistics for localized corrosion showed that the depth of pit in 1Cr-X65 was much shallower than that of API-X65. The order of the resistance to general and localized corrosion was: l6Mn＞1Cr-X65＞API-X65. The excellent resistance to CO2 corrosion of 16Mn possibly derives from the periodic protuberant boundary formed by the preferential solution of ferrite. The remainder lamellar cementite helps anchor FeCO3 film to the substrate. This interlocking structure endue l6Mn with excellent resistance to hydrodynamical destroy. The shear intensity of corrosion scales of l6Mn was higher than that of API-X65.