High-temperature oxidation of Q235 low-carbon steel treated by plasma electrolytic borocarburizing

The high-temperature oxidation behaviors of Q235 low-carbon steel treated by plasma electrolytic borocarburizing (PEB/C) method were evaluated at 500 °C and 600 °C in air for 100 h. SEM and XRD were performed to investigate the surface morphologies, microstructures and phase constituents of steel substrate and PEB/C samples after isothermal oxidation tests. The results showed that the PEB/C steels had much lower weight gain than the untreated substrate under isothermal oxidation of 500 °C and 600 °C. The oxidation resistance of PEB/C steel with different thickness of boride layer was similar. At 600 °C, the final weight gain of PEB/C samples is 4-5 times lower than that of bare steel substrate. This was attributed to the formation of Fe2B phase with good thermal stability in the boride layer, which had high oxidation resistance at high temperature environment. Plasma electrolytic borocarburizing is a promising method to improve the oxidation resistance of steels.