Search

In this study, the DED-LB/M process of AISI H11 tool steel powder blends modified by adding WC nanoparticles (WC-np) in concentrations of 1, 2.5 and 5 wt.-% was the object of scientific investigations. For this, 30-layer cuboid specimens were manufactured. The overall scientific aim was to examine how the WC-np interact with the steel melt and in the end, influence the processability, microstructure and mechanical properties of produced specimens. The examinations were carried out on both as-built and thermally post-processed specimens. An advanced microstructural analysis (SEM, EDS, EBSD and XRD) revealed that due to the high solubility of WC-np in the molten steel, most of the WC-np appear to have dissolved during the ongoing laser process. Furthermore, the WC-np favor a stronger distortion and finer grain size of martensite in the manufactured specimens. An increase in hardness from about 650 HV1 for the H11 specimen to 780 HV1 for the one manufactured using the powder blend containing 5 wt.-% of WC-np was observed in as-built conditions. In the same way, the compression yield strength enhanced from 1839 MPA to 2188 MPA. The hardness and strength increasing effect of WC-np remained unchanged even after heat treatments similar to those used in industry.

In this study, the DED-LB/M process of AISI H11 tool steel powder blends modified by adding WC nanoparticles (WC-np) in concentrations of 1, 2.5 and 5 wt.-% was the object of scientific investigations. For this, 30-layer cuboid specimens were manufactured. The overall scientific aim was to examine how the WC-np interact with the steel melt and in the end, influence the processability, microstructure and mechanical properties of produced specimens. The examinations were carried out on both as-built and thermally post-processed specimens. An advanced microstructural analysis (SEM, EDS, EBSD and XRD) revealed that due to the high solubility of WC-np in the molten steel, most of the WC-np appear to have dissolved during the ongoing laser process. Furthermore, the WC-np favor a stronger distortion and finer grain size of martensite in the manufactured specimens. An increase in hardness from about 650 HV1 for the H11 specimen to 780 HV1 for the one manufactured using the powder blend containing 5 wt.-% of WC-np was observed in as-built conditions. In the same way, the compression yield strength enhanced from 1839 MPA to 2188 MPA. The hardness and strength increasing effect of WC-np remained unchanged even after heat treatments similar to those used in industry.

In this study, the DED-LB/M process of AISI H11 tool steel powder blends modified by adding WC nanoparticles (WC-np) in concentrations of 1, 2.5 and 5 wt.-% was the object of scientific investigations. For this, 30-layer cuboid specimens were manufactured. The overall scientific aim was to examine how the WC-np interact with the steel melt and in the end, influence the processability, microstructure and mechanical properties of produced specimens. The examinations were carried out on both as-built and thermally post-processed specimens. An advanced microstructural analysis (SEM, EDS, EBSD and XRD) revealed that due to the high solubility of WC-np in the molten steel, most of the WC-np appear to have dissolved during the ongoing laser process. Furthermore, the WC-np favor a stronger distortion and finer grain size of martensite in the manufactured specimens. An increase in hardness from about 650 HV1 for the H11 specimen to 780 HV1 for the one manufactured using the powder blend containing 5 wt.-% of WC-np was observed in as-built conditions. In the same way, the compression yield strength enhanced from 1839 MPA to 2188 MPA. The hardness and strength increasing effect of WC-np remained unchanged even after heat treatments similar to those used in industry.

In this study, the DED-LB/M process of AISI H11 tool steel powder blends modified by adding WC nanoparticles (WC-np) in concentrations of 1, 2.5 and 5 wt.-% was the object of scientific investigations. For this, 30-layer cuboid specimens were manufactured. The overall scientific aim was to examine how the WC-np interact with the steel melt and in the end, influence the processability, microstructure and mechanical properties of produced specimens. The examinations were carried out on both as-built and thermally post-processed specimens. An advanced microstructural analysis (SEM, EDS, EBSD and XRD) revealed that due to the high solubility of WC-np in the molten steel, most of the WC-np appear to have dissolved during the ongoing laser process. Furthermore, the WC-np favor a stronger distortion and finer grain size of martensite in the manufactured specimens. An increase in hardness from about 650 HV1 for the H11 specimen to 780 HV1 for the one manufactured using the powder blend containing 5 wt.-% of WC-np was observed in as-built conditions. In the same way, the compression yield strength enhanced from 1839 MPA to 2188 MPA. The hardness and strength increasing effect of WC-np remained unchanged even after heat treatments similar to those used in industry.

In this study, the DED-LB/M process of AISI H11 tool steel powder blends modified by adding WC nanoparticles (WC-np) in concentrations of 1, 2.5 and 5 wt.-% was the object of scientific investigations. For this, 30-layer cuboid specimens were manufactured. The overall scientific aim was to examine how the WC-np interact with the steel melt and in the end, influence the processability, microstructure and mechanical properties of produced specimens. The examinations were carried out on both as-built and thermally post-processed specimens. An advanced microstructural analysis (SEM, EDS, EBSD and XRD) revealed that due to the high solubility of WC-np in the molten steel, most of the WC-np appear to have dissolved during the ongoing laser process. Furthermore, the WC-np favor a stronger distortion and finer grain size of martensite in the manufactured specimens. An increase in hardness from about 650 HV1 for the H11 specimen to 780 HV1 for the one manufactured using the powder blend containing 5 wt.-% of WC-np was observed in as-built conditions. In the same way, the compression yield strength enhanced from 1839 MPA to 2188 MPA. The hardness and strength increasing effect of WC-np remained unchanged even after heat treatments similar to those used in industry.

Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 degrees C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, similar to 0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 degrees C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.

Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.

Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 degrees C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, similar to 0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 degrees C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.

Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.

Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 degrees C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, similar to 0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 degrees C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.

Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.

Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 degrees C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, similar to 0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 degrees C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.

Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.

Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 degrees C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, similar to 0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 degrees C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.

Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.