The crystalline structure and mechanical properties of titanium 6Al 4V produced via selective laser sintering were compared to literature examples and to wrought samples. In total, three sets of samples were analyzed:...The crystalline structure and mechanical properties of titanium 6Al 4V produced via selective laser sintering were compared to literature examples and to wrought samples. In total, three sets of samples were analyzed: wrought, as printed selective laser sintering samples with no post processing, and selective laser sintering samples that were further processed via hot isostatic pressing for final consolidation. Samples were sectioned to fit on graphitic resin pucks and cut from the build plane in two orthogonal planes. Images were taken using a TESCAN MIRA3 scanning electron microscope with electron backscatter diffraction analysis and samples were etched for optical analysis. Hardness of the samples was measured using a Vickers hardness indenter. The overall chemical composition of the samples, both AM and wrought, were similar as confirmed using energy dispersive spectroscopy. Beta grains were observed in a columnar orientation along the build direction, however, the grain orientation did not appear to affect the hardness of the sample. A small amount of grain growth was observed in the post processed samples as compared to the as printed samples.展开更多
In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to redu...In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to reduce frictional forces thereby reducing tool wear and increasing welding speeds. Differences in microstructures within heat affected zones were identified at specific laser powers and traverse speeds. Vickers hardness values were recorded and analyzed to validate the formation of additional martensite in diode laser heated regions of HY-80 steel. Conditions that produced little to no additional martensite were identified and relationships among high power diode laser power, traverse speed, and martensite formation were determined. The development of heat affected zones, change in grain structure, and creation of additional martensite in HY-80 can be prevented through the optimization of laser amperage and transverse speed.展开更多
文摘The crystalline structure and mechanical properties of titanium 6Al 4V produced via selective laser sintering were compared to literature examples and to wrought samples. In total, three sets of samples were analyzed: wrought, as printed selective laser sintering samples with no post processing, and selective laser sintering samples that were further processed via hot isostatic pressing for final consolidation. Samples were sectioned to fit on graphitic resin pucks and cut from the build plane in two orthogonal planes. Images were taken using a TESCAN MIRA3 scanning electron microscope with electron backscatter diffraction analysis and samples were etched for optical analysis. Hardness of the samples was measured using a Vickers hardness indenter. The overall chemical composition of the samples, both AM and wrought, were similar as confirmed using energy dispersive spectroscopy. Beta grains were observed in a columnar orientation along the build direction, however, the grain orientation did not appear to affect the hardness of the sample. A small amount of grain growth was observed in the post processed samples as compared to the as printed samples.
文摘In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to reduce frictional forces thereby reducing tool wear and increasing welding speeds. Differences in microstructures within heat affected zones were identified at specific laser powers and traverse speeds. Vickers hardness values were recorded and analyzed to validate the formation of additional martensite in diode laser heated regions of HY-80 steel. Conditions that produced little to no additional martensite were identified and relationships among high power diode laser power, traverse speed, and martensite formation were determined. The development of heat affected zones, change in grain structure, and creation of additional martensite in HY-80 can be prevented through the optimization of laser amperage and transverse speed.
