In order to enhance the nitriding efficiency

42CrMo steel was selected as the testing material. Plasma oxynitriding using different air flow in the same pulsed plasma nitriding system for 42CrMo steel was investigated innovatively

and compared with conventional plasma nitriding processing. The cross-sectional microstructures

phases

corrosion resistance were determined by optical microscopy

X-ray diffraction

microhardness tester and electrochemical workstations. The results show that plasma oxynitriding owns much higher efficiency compared with plasma nitriding

thus makes thicker compound layer under the same other conditions. Meanwhile

higher porosity of nitrided layer is obtained. Furthermore

corrosion resistance can be significantly improved due to chemically stable formation and compact Fe

3

O

4

oxi

de in the compound layer during plasma oxynitriding process

and air flow of 0.3L/min offers the optimum performance for 42CrMo steel due to highest ratio of Fe

3

O

4

to Fe

2

O

3

. This research can provide a reference for improving the surface modification process of 42CrMo.