Effect of oxide film on tribological properties at room temperature and corrosion performance of QPQ nitride layers on 14Cr12Ni2WMoVNb steel

This study analyzed the effects of the oxide film of 14Cr12Ni2WMoVNb steel with QPQ (quench-polish-quench) treatment on tribological properties at room temperature and corrosion resistance of the layers. The microstructure and properties of specimens with and without oxide film were studied by metallographic analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), a scratch tester, friction and wear tester, and at an electrochemical workstation. Results show that the effects of the oxide film on tribological properties of the layers are related to load. When the friction time is 4 min and the load is low (50 N), the friction coefficient of the oxide film and the volume wear rate are effectively decreased. However, with a friction time of 4 min and a high load (100 N), the oxide film is destroyed, there is thus no reduction in the volume wear rate. The study also shows that the oxide film obviously improves the corrosion resistance of the layers. The Tafel polarization curve of the specimen with oxide film has an obvious passivation region, and the pitting potential is-13 mV. The surface of the specimen with the oxide film removed has a wide area of corrosion after salt spray corrosion for 12 h, whereas a large area of corrosion only occurs after 48 h of salt spray for the specimen with the oxide film.