Three-layer deposited metal is prepared on Q345 steel by arc welding with φ3.2 mm electrode D628. Microstructure and properties of deposited metals are analyzed by using optical microscopy

scanning electron microscopy（SEM）

microhardness tester and impact test. The results show that the microstructure of surfacing layer is mainly composed of cementite lamellae and pearlite on ledeburite matrix

the microstructure of heat affected zone is uniform and fine. As the number of surfacing layers increases

the average hardness value improves from 628.34 HV to 677.62 HV

the hardness of the third layer of surfacing layer is closed to that of second layer

and the average value is above 650 HV. The main reason is as the number of layers increases

the dilution effect of matrix on deposited metal weakens and the ratio of carbides in surfacing layer increases. The impact fracture analysis shows that the fracture mode changes from ductile fracture to quasi-cleavage fracture from the substrate to surfacing layer.