Achieving Refined Overlay Microstructure of a Zn-55Al-3Mg-1.5Si Coating Using High Power Diode Laser (HPDL) Surface Treatment
C-T. Peng, M. U. Forthan, Z. Chen, Q. Liu, D. Nolan, H. Li, M. Liu and R. Luo
A high power diode laser (HPDL) was successfully used as a surface modifying approach on a hot dip process simulator (HDPS) Zn-55Al-3Mg-1.5Si coating. The overlay microstructure was drastically refined owing to the rapid cooling rate of the laser radiation process, in which the size of α-Al dendrite was shrunk to less than 1/10 of the original. The laser also varied the solidifying path and yielded different phases in the interdendritic areas leading to modifications including, rare Si, disappearance of MgZn2 and nucleation of the Q phase. The modified Zn-55Al-3Mg-1.5Si coating induced by HPDL surface treatment is assumed to make a contribution to the improvement of the corrosion resistance.
Keywords: High power diode laser (HPDL), steel, Al-Zn coating; Zn-Al-Mg-Si system, hot dip process simulator (HDPS), overlay microstructure, phase