高铬铸铁钻井泵缸套之磨损机理与新型缸套的研究

Study on Wear Mechanism of High-Chromium Cast Iron Liner and New Model Liner

本文对不同地区使用失效的10只高铬铸铁钻井泵缸套严重磨损表面进行了金相分析、扫描电子显微镜形貌分析和磨屑的铁谱分析,进而对缸套的磨损失效过程和起主导作用的磨损机理作了探讨,提出了具有一定理论价值和实用意义的新观点。文章根据缸套材质的匹配试验结果指出,缸套的含Cr量以10％(ωt)左右为最佳,既能保证其具有良好的耐磨性而延长使用寿命,又能减少Cr的用量而使成本降低17.85％。按照本文提供的数据资料制造的新型钻井泵缸套已经在四川石油管理局川西南矿区投入使用,效果良好。

Mud pump liner is the key parts of oil development equipment. Because of the severe operating conditions, its service life is very short. With high-chromium cast iron used for liner, its life may increase significantly, but the mineral resources of our country are short of chromium. This paper analyzes ten high- chromium cast iron liners serviced and worn out in different region, it involves mettallographic analysis of worn-out surfaces, analysis of surface topographies by scanning electron microscope and wear debris analysis. By discussing the failure process and essential wear mechanism, some new conceptions of theoretical and practical significance are presented. It is pointed out that the wear out of martensitic matrix of high-chromium cast iron results in break and collapse of convex carbides owing to lossing support. As a result of collapse of carbides, matrix losses support and falles in rapid wear out. When carbides appear again on the working surface, the matrix comes into slow wear out. Then, matrix wear out, convex carbides appear, break and collapse, and new rapid wear out results. Because of this repeated process, the high-chromium cast iron liner wears out unceasingly and failure at last. It may be concluded that the essential failure mechanism of high-chromium cast iron liner is owing to break and collapse of carbides. Based on the results of material-matching tests, it is pointed out that the best chromium content is about 10%, by which it is not only ensuring the good wear-resistance, but also reducing cost by 17. 85% from the decreased chromium content. The new model liner, manufactured according to the data of this paper, has been efficiently used in South west-Sichuan Oil Field.