Abstract
A fiber laser was used to nitride Ti–6Al–4V titanium alloy the effect of the process parameters on the surface morphology was studied. The surface chemical composition of the nitride layer and the phase of black powder on the surface were analyzed, the two-dimensional and three-dimensional surface topography of the nitride layer surface were measured, and the cross-section microstructure of the nitride layer was photographed. The effects of laser power, laser scanning speed, nozzle distance, and nitrogen flow rate on the surface morphology were studied. The experiments show that the laser power mainly affects the surface oxidation, the laser scanning speed mainly affects the surface roughness, and the nozzle distance has a great influence on the surface morphology. The gas flow rate, however, had a slight effect on the surface morphology. A large heat input and a high nitrogen flow rate caused an increase in TiN and TiO2 black powders. Surface oxidation did not affect the formation of a continuous TiN layer nor surface roughness. Finally, the critical energy density leading to increased surface roughness was calculated.
Highlights
The traditional steam turbine blade is made of stainless steel
The effects of fiber laser power, laser scanning scanning speed,flow nitrogen flownozzle rate, and nozzleondistance on the surface morphology of layer the nitride speed, nitrogen rate, and distance the surface morphology of the nitride were layer were studied in this research project
There were black powders on the surface, which weakly adhered to titanium alloy and could be wiped off with a towel
Summary
The traditional steam turbine blade is made of stainless steel. With the development of steam turbine technology, the blade became larger and heavier; this meant that the centrifugal force of the turbine was close to the allowable stress of the stainless steel. The microstructure and components of the nitride layer are related to laser power, laser scanning speed, and nitrogen gas flow rate [4]. The nitride layer’s properties and morphology are a function of such processing parameters as laser power and laser scanning speed [5,6]. Sathish et al [9] found that a high laser scanning speed made the nitride layer smooth and crack-free, whereas Singh et al [10]. The effects of fiber laser power, laser scanning scanning speed,flow nitrogen flownozzle rate, and nozzleondistance on the surface morphology of layer the nitride speed, nitrogen rate, and distance the surface morphology of the nitride were layer were studied in this research project.
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