Surface Structure and Corrosion Resistance of Carbon Steel Treated by AIH-MFPP Using Mixed Shot Particles of Chromium (Cr) and High Speed Steel (SKH59)

Abstract

In this study, a new surface modification process, an atmospheric-controlled induction-heating multiple-fine-particle peening (AIH-MFPP) using mixed two kinds of shot particles, was proposed. In order to investigate the effects of AIH-MFPP, the surface of carbon steel was modified with mixed shot particles of chromium (Cr) and high speed steel (SKH59) at 900°C in argon atmosphere. The treated surfaces were characterized using a field emission- scanning electron microscope (FE-SEM), an energy dispersive X-ray spectrometer (EDX), an X-ray diffractometer (XRD) and an X-ray photoelectron spectroscope (XPS). In the case of the specimen treated by using mixed shot particles of Cr and SKH59, a relatively thick and uniform Cr rich layer was formed at the surface. The thickness of the Cr rich layer was changed with an increase in peening pressure. In the case of a specific mixed-ratio of shot particles, not only was the thickness of the Cr rich layer changed at the surface, but also the crystal structure was changed. This specimen showed higher corrosion resistance compared to that of the specimen treated by using Cr shot particle only. Moreover, there was the electrical current density of the passive state. This indicates that passive film was generated by AIH-MFPP. This was because the Cr rich layer created by AIH-MFPP was covered with a passive film of FeOOH. These results suggest that a new surface modification process ; AIH-MFPP, is promising for the improvement of the corrosion resistance of carbon steel.