高能喷丸处理对15CrMo低合金钢常温黑色转化膜特性的影响

Effects of High-energy Shot Peening on Characters of Normal-temperature Black Conversion Film of 15CrMo Low-alloy Carbon Steel

采用高能喷丸的方法在15CrMo低合金钢表面获得剧烈变形层达到组织细化的效果,在喷丸处理前后试样表面分别制备常温黑色转化膜。利用扫描电子显微镜及能谱仪分析转化膜的形貌及组成,采用全浸泡、动电位极化和电化学阻抗谱方法测试转化膜在3.5%NaCl溶液中耐蚀性。结果表明,高能喷丸处理后15CrMo低合金钢表层组织显著细化,组织更加均匀,促进了结晶颗粒细小、致密的黑色转化膜的形成。与未经喷丸处理试样表面的转化膜相比,高能喷丸处理提高了15CrMo钢表面黑色转化膜的耐蚀性,表现为自腐蚀电位提高90mV,自腐蚀电流密度降低60%,耐盐水浸泡时间延长。

A severely deformed layer with refined grains was fabricated on 15CrMo lowalloy carbon steel by highenergy shot peening. A conversion film was prepared on the surface of 15CrMo steel before and after peening by normal temperature blackening. The morphology and composition of the film was analyzed by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）, and their corrosion properties were studied using immersion, potentiodynamic polarization and electrochemical impedance spectroscopy methods in a 3.5% NaCl solution. Results show that after highenergy shot peeing, the microstructures of the deformed layer in 15CrMo steel are remarkably refined and well homogenized. The highenergy shot peening can promote the formation of a denser and finer conversion film. Compared with that of the conversion film on the untreated steel, the corrosion resistance of the conversion film on the 15CrMo steel is enhanced by highenergy shot peening of the steel, as the free corrosion potential is improved by 90 mV, the free corrosion current density is reduced by 60%, and the time of tolerance to salt water submersion is increased.