超声喷丸对钢基体表面发黑膜耐蚀性的影响

目的通过对低碳钢基体进行超声喷丸前处理来提高其表面高温碱性发黑膜的耐蚀性。方法采用超声喷丸的方法在低碳钢表面获得剧烈变形层,达到组织细化的效果,并分别在超声喷丸处理前后的钢表面制备高温碱性发黑膜。通过微观观察、电化学极化曲线、电化学阻抗谱测试及全浸泡腐蚀试验,研究喷丸处理对转化膜形貌和耐蚀性的影响。结果超声喷丸处理后,钢基体表层组织显著细化、均匀化,喷丸表面形成的发黑膜结晶颗粒细小、均匀、致密。该膜层与未喷丸表面的发黑膜相比,自腐蚀电位提高了170 m V,自腐蚀电流密度降低了85%,膜层电阻增大1倍以上,并且耐盐水浸泡能力增强。结论超声喷丸的方法可以用于低碳钢表面的前处理,以提高其后续发黑膜的耐蚀性。

Effect of Ultrasonic Shot Peening on Corrosion Resistance of Steel Substrate Surface Blackening Film

The work aims to improve the corrosion resistance of high temperature alkaline black film on low-carbon steel substrate processed by ultrasonic shot peening. The severe deformation layer was obtained by ultrasonic shot peening on the surface of low-carbon steel to achievegrain refined structure. The alkaline black films were prepared on the shot-peened and unshot-peened samples. The effects of shot peening on the morphology and corrosion resistance of the coatings were studied through microscopic observation, electrochemical polarization curve, electrochemicalimpedance spectroscopy and immersion test. The microstructure of the surface of low-carbon steel was significantly refined and more uniform after the ultrasonic shot peening. The ultrasonic shot peening promoted the formation of fine, uniform and compactmicrostructure of the black film. Compared with the black film on unshot-peened samples, after ultrasonic shot peening, the free corrosion potential of the film increased by 170 mV, the corrosion current density reduced by 85%, film resistance increased by 1 time and the ability of resistance to salt waterwas improved. The ultrasonic shot peening can be used in the surface pretreatment of the low-carbon steel to improve the corrosion resistance of the subsequent black film.