Strengthening of 304 Stainless Steel Surface with Ni25 and Stellite 6 Nanocrystalline Laser Clad Coatings
Y. Tian, Z. Zhang, J-N. LI, F. Cao, Z-Y. Ye, Z-P. Zou, S-B. Xu, B. Zhao and C-N. JING
Ni25 and Stellite 6 coatings were prepared by means of a laser cladding with a high power diode laser (HPDL) in order to improve the surface quality of 304 stainless steel. Microstructure and properties were characterized by using a scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), microhardness testing and wear testing. Experimental results showed that large amounts of the ceramics can be produced in the Stellite 6 laser clad, enhancing the microhardness and wear resistance of the of this coating, which was higher than both the Ni25 laser clad and the 304 stainless steel substrate. W and C present in Stellite 6 led to significant amounts of nanoscale crystals to be formed, resulting in an extremely fine micro- structure. The Stellite 6 laser clad coating exhibited a better wear resistance than that of the Ni25 laser clad coating owing to the abrasive wear and microploughing.
Keywords: High power diode laser (HPDL), 304 stainless steel, Ni25, Stellite 6, laser cladding, coatings, nanocrystalline materials, microstructure, microhardness, wear