The effect of Si addition on microstructure and tribological properties of Fe-Al claddings produced by GTAW process

In this research, microstructure and tribological properties of CK45 steel coated with Fe-Al and Fe-Al-Si alloys using GTAW process were studied. In order to evaluate the microstructure and formed phases in the claddings, optical microscopy and X-ray diffractometery analysis were used. Also, tribological properties of the claddings were evaluated by pin-on-disk wear test at two different temperatures of 25 and 500 oC. Finally, the wear surfaces after the wear test were characterized by scanning electron microscopy to detect the main wear mechanism. It was found that the microstructure of Fe-Al-Si cladding was dendritic and lathy in some areas, while in Fe-Al cladding blade shape microstructure was seen. In Fe-Al-Si cladding owing to the presence of Si element, the width of cellular and planar solidification area was lower and dendritic solidification was seen. XRD analysis revealed that the main phase in Fe-Al binary and Fe-Al-Si ternary claddings were Fe3Al and (Fe,Si)3Al intermetallic compounds, respectively. Fe-Al-Si cladding indicated higher microhardness and wear resistance as compared with Fe-Al cladding. With addition of Si into the surface owing to microstructure refining and formation of (Fe,Si)3Al complex intermetallic compound the wear behavior of the surface improved. The predominant wear mechanism of both claddings was adhesion at room temperature, but at 500 oC, the predominant wear mechanism in Fe-Al cladding was micro-plowing abrasive while in Fe-Al-Si cladding was adhesive and abrasive.