Laser Cladding of Fe-Cr-C Alloys on A5052 Aluminum Alloy Using Diode Laser

摘要

In order to improve a wear resistance of aluminum alloy, we proposed a diode laser cladding of iron-based alloy on the surface of an aluminum alloy. In the first part of this research, an applicability of diode laser to laser cladding was evaluated. In this experiment, irradiation conditions were varied to investigate the effect of process parameters on the formation of clad layers. From this result, application of diode laser made it possible to obtain stable beads in low heat input compared with CO_2 laser, which has been conventionally used for laser cladding. Secondly, we investigated effects of the irradiation conditions on the dilution ratio and the microstructure of a Fe-Cr-C clad layer. It was confirmed that decrease in laser power and increase in traverse speed made the dilution ratio suppressed. According to the increase in aluminum content in the clad layer, the microstructure of the clad layer changed as gamma (8-20 percent)-gamma+alpha (10-30 percent)- > Fe_3Al(30 percent-). At the interface between the clad layer and the aluminum alloy substrate, the reaction layer consisting of Fe_2Al_5 and FeAl_3 formed. The obtained complex frequently included cracks within the clad layer or in the reaction layer, each of which was caused by different factors. The cracks in the clad layer decreased with decreasing the hardness of the clad layer and formation of the ferrite in the austenite phase, which was achieved by controlling the dilution ratio and the carbon content of the cladding material. With respect to the interface cracks, it was found that the addition of copper for reduction of the thermal stress arising at the interface had a beneficial effect on suppressing the interface cracks. In the abrasion Fe-Cr-C and the Fe-Cr-Cu-C clad layers exhibited a higher wear resistance compared with the aluminum alloy.