Microstructure and Properties of Surface Laser Cladding Fe-Base Alloy Layer on Ductile Cast Iron

Laser cladding of Fe-based alloy layer on QT-500 ductile cast iron surface was carried out by DL-T5000 CO2 laser. The microstructure, microhardness and wear resistance of the laser cladding layers were analyzed and tested. The results show that the cladding layers had compact and flawless microstructure that had been integrated metallurgical bonding with substrate. Microstructure of the cladding zone consisted of massive branch crystal, equiax crystal and branch crystal in turn from the surface of cladding layers to heat-affected zone. The microhardness of the layers increased 2.5 times campared with that of the substrate and the abrasion weight was one third of that for the substrate. The reasons of the wear resistance improving were mainly strength due to solid solution formation of elements Ni and Cr to Fe-based alloy and carbides.