Abstract
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H13 tool steel samples were prepared using directed energy deposition (DED) and were then pack-borided at temperatures of 800°C, 850°C, 900°C, or 950°C, with a hold time of 4 hours for each temperature. As a baseline, wrought H13 tool steel samples were also pack-borided under identical conditions. The microstructures and crystalline phases for the borided samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDS), hardness, and confocal laser scanning microscope (CLSM). After applying the thermochemical heat-treatment to the tool steel samples, a characteristic ‘saw-tooth’ appearance of the boride layer is observed in the cross-section of all samples, which is slightly flattened due to the high alloying in the tool steel. This boride layer consists of a FeB layer (tensile) on the outer surface, with a Fe2B layer (compressive) below. With increasing boriding temperature, the borided layer increased in thickness. WDS confirmed that the elements Si, C, and Cr were redistributed due to the formation of the boride layer. It was observed that the boriding process significantly improved the hardness of the samples. There was no clear trend in terms of the surface roughness after boriding at the various temperatures, with samples processed at 900°C having the highest surface roughness. The surface of as-borided samples shows a porous appearance with cracking due to the residual tensile stresses of the FeB layer.
H13 tool steel samples were prepared using directed energy deposition (DED) and were then pack-borided at temperatures of 800°C, 850°C, 900°C, or 950°C, with a hold time of 4 hours for each temperature. As a baseline, wrought H13 tool steel samples were also pack-borided under identical conditions. The microstructures and crystalline phases for the borided samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDS), hardness, and confocal laser scanning microscope (CLSM). After applying the thermochemical heat-treatment to the tool steel samples, a characteristic ‘saw-tooth’ appearance of the boride layer is observed in the cross-section of all samples, which is slightly flattened due to the high alloying in the tool steel. This boride layer consists of a FeB layer (tensile) on the outer surface, with a Fe2B layer (compressive) below. With increasing boriding temperature, the borided layer increased in thickness. WDS confirmed that the elements Si, C, and Cr were redistributed due to the formation of the boride layer. It was observed that the boriding process significantly improved the hardness of the samples. There was no clear trend in terms of the surface roughness after boriding at the various temperatures, with samples processed at 900°C having the highest surface roughness. The surface of as-borided samples shows a porous appearance with cracking due to the residual tensile stresses of the FeB layer.
Microstructural Characterization of Pack Borided H13 Tool Steel Processed Using Directed Energy Deposition
Disclosure(s): None
Owen Craig
Abstract
Discussion Forum (0)
H13 tool steel samples were prepared using directed energy deposition (DED) and were then pack-borided at temperatures of 800°C, 850°C, 900°C, or 950°C, with a hold time of 4 hours for each temperature. As a baseline, wrought H13 tool steel samples were also pack-borided under identical conditions. The microstructures and crystalline phases for the borided samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDS), hardness, and confocal laser scanning microscope (CLSM). After applying the thermochemical heat-treatment to the tool steel samples, a characteristic ‘saw-tooth’ appearance of the boride layer is observed in the cross-section of all samples, which is slightly flattened due to the high alloying in the tool steel. This boride layer consists of a FeB layer (tensile) on the outer surface, with a Fe2B layer (compressive) below. With increasing boriding temperature, the borided layer increased in thickness. WDS confirmed that the elements Si, C, and Cr were redistributed due to the formation of the boride layer. It was observed that the boriding process significantly improved the hardness of the samples. There was no clear trend in terms of the surface roughness after boriding at the various temperatures, with samples processed at 900°C having the highest surface roughness. The surface of as-borided samples shows a porous appearance with cracking due to the residual tensile stresses of the FeB layer.
H13 tool steel samples were prepared using directed energy deposition (DED) and were then pack-borided at temperatures of 800°C, 850°C, 900°C, or 950°C, with a hold time of 4 hours for each temperature. As a baseline, wrought H13 tool steel samples were also pack-borided under identical conditions. The microstructures and crystalline phases for the borided samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDS), hardness, and confocal laser scanning microscope (CLSM). After applying the thermochemical heat-treatment to the tool steel samples, a characteristic ‘saw-tooth’ appearance of the boride layer is observed in the cross-section of all samples, which is slightly flattened due to the high alloying in the tool steel. This boride layer consists of a FeB layer (tensile) on the outer surface, with a Fe2B layer (compressive) below. With increasing boriding temperature, the borided layer increased in thickness. WDS confirmed that the elements Si, C, and Cr were redistributed due to the formation of the boride layer. It was observed that the boriding process significantly improved the hardness of the samples. There was no clear trend in terms of the surface roughness after boriding at the various temperatures, with samples processed at 900°C having the highest surface roughness. The surface of as-borided samples shows a porous appearance with cracking due to the residual tensile stresses of the FeB layer.
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