Effects of Tempering and Y2O3 Content on the Microstructure and Wear Characteristics of a Laser Metal Deposition (lMd) Composite Coating on a Titanium Alloy
J-N. Li, T-G. Zhai, Y-B. Zhang, K-G. Liu, P. Liu, Y.S. Huo and C.C. Jiang
Laser melting via laser metal deposition (LMD) of a Stellite SF12-TiC Y2O3 mixed powder composite coating onto a TA1 Ti-alloy substrate formed nanocrystals reinforced hard composite coating, which increased the wear resistance of the substrate greatly. Experimental results indicated that lots of the nanocrystalline/amorphous phases were produced in such coating. After the tempering process, an uniform and fine compact composite coating was obtained, and the microhardness increased accordingly. When an excess of Y2O3 content was added in the pre-placed coating a great number of the crystals disappeared, resulting in the formation of microcracks. The tempering is able to remove the accumulation of the residual stress in a certain extent, improving the plastic and toughness properties of such LMD coating, leading to an improvement of wear resistance.
Keywords: CO2 laser, Stellite, Y2O3, titanium alloy, laser metal deposition (LMD), composite coating, tempering, nanocrystalline, amorphous, wear, coefficient of friction (COF), residual stress