Microstructure and properties of nitrided layer of titanium plate, produced by simultaneous laser quenching and liquid-nitrogen cryogenics

In the present study, titanium plate was treated by a novel method of laser quenching, simultaneously combined with liquid-nitrogen cryogenics (LQLNC). The microstructure and properties of the titanium plate after treatment were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, Vickers hardness testing, and friction wear testing. The results show that the treated titanium plate is covered by a nitrided layer with a homogeneous thickness of about 60 μm, while the nitrided layer consists of TiN and α-Ti phases. Compared to general laser quenching, the LQLNC treatment increases the hardness and wear resistance of the surface-modified layer of the titanium plate. As a result of grain refinement in the nitrided layer, the cracking induced by the rapid solidification of the conventional laser-quenching process has also been effectively solved.