Tool wear and surface roughness during machining of high-temperature aluminized steel

The machinability of high-temperature aluminized steel, wherein hot-dip aluminum-coated steel is heated to 1000 °C, was investigated by machining the material using a cemented carbide tool. It was confirmed that the alloy layer formed by the high-temperature aluminizing consisted of an Fe2Al5 layer, an FeAl layer and an aluminum solid solution (αFe(Al)). With increasing diffusion time, the thickness of the FeAl layer and the αFe(Al) layer increased while the thickness of the Fe2Al5 layer decreased. During the machining of the aluminized steel at a cutting speed of 1.5 m/s, the tool temperature rose rapidly, in particular during cutting of the FeAl layer. Flank wear during cutting of the Fe2Al5 layer was not greatly affected by changing the cutting speed. In contrast, flank wear during cutting of FeAl was smaller at a lower cutting speed. The machined surface roughness was larger for cutting of the Fe2Al5 layer and the FeAl layer region because of brittle fracture on the machined surface, whereas it decreased with increasing distance from the surface to a minimum at the αFe(Al) layer region.