Investigation of surface properties and wear behavior of boro-tempered AISI 1040 steel

Surface properties and wear behavior of borotempered AISI 1040 steel are investigated in this study. Disc shaped samples embedded in EKABOR®2 powder were boronized at 900 ºC for 1, 3, and 5 hours. Following the boronizing, immediately a tempering treatment was applied to the samples for 1 hour in a salt bath at 250 ºC, 350 ºC, and 450 ºC. All the samples cooled down to the room temperature were washed with water and dried. A number of boronized samples were not tempered in order to make comparisons between only boronized and borotempered materials. Three sets samples were prepared in this study; untreated, boronized, and borotempered. Selected samples from these three groups were investigated for microstructure by optical microscopy. A coating top layer and matrix were analyzed by X-ray diffraction (XRD) for phase structure, and also thicknesses were determined. Boronized and borotempered samples were tested for wear behavior by ball-on disc tests under 10 N and 20 N loads. Wear rates were determined from wear lines and scanning electron microscopy (SEM) was also used in order to study wear type. All the results observed in this study show that both the microstructure and wear behavior of AISI 1040 steel change with borotempering treatment conditions. Even though structure and composition of the coating layer is the same for both boronized and borotempered samples, matrix structures are found to be different. In general, increasing load and decreasing boronizing temperature correspond to higher wear rates.Key Words: AISI 1040 Steel, Boronizing, Borotempering, Wear.