By introducing design of experiment (DOE), we examined the effect of processing parameters, such as peening pressure, particle supply rate, peening time, and heating time, on the characteristics of modified layers. The surface of structural steel was modified by AIH-FPP with Cr shot particles at 900 °C in an argon atmosphere. Results showed that the peening time strongly affected the levels of oxygen concentration at the treated surface; the longer the peening time, the higher the oxygen concentration. Heating time also affected the Cr concentration at the surface; the longer the heating time, the higher the Cr concentration. Corrosion tests were performed using a three-electrode electrochemical cell connected to a computer driven potentiostat. The specimens with Cr diffused layers showed higher corrosion resistance compared to other specimens. This is because of the existence of passive films on treated surfaces.
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