Study on Surface Roughness Improvement of Selective Laser Melted Ti6Al4V Alloy

Abstract

To improve the surface quality of Ti6Al4V parts formed by selective laser melting (SLM), this paper systematically studies the effects of laser power, scanning speed and inclination angle on the different surface morphology and roughness of parts. On this basis, the effect of surface remelting and multi-layer profile scanning process strategies on improving the surface quality of parts is explored. The upper surface roughness varies parabolically with increasing line energy density, the line energy density value that minimizes the upper surface roughness is around 0.22 J/mm, and the minimum Ra value is 4.41 μm. The roughness of upper and lower sides increases significantly with the increase in scanning speed. As the inclination angle increases, the roughness of the upper and lower sides gradually decreases, which is caused by the combined influence of powder adhesion and step effect. The surface remelting process strategy can reduce the upper surface roughness by 35.68% and reduce its Ra value to 2.65 μm. The multi-layer profile scanning process strategy can reduce the upper side and vertical side roughness by more than 50%, down to Ra 5.10 μm and Ra 4.61 μm, respectively.

Optimising Surface Roughness and Density in Titanium Fabrication via Laser Powder Bed Fusion

“…This reduction can be attributed to the improved consolidation of metal powder which improved the interlayer connection and eliminated the presence of spatter particles on the surface. As a result, a superior top surface finish is achieved [ 38 , 39 ]. Furthermore, the higher laser power also enhanced the wettability of the sample melt pool, thereby reducing disparities in surface tension.…”

“…This improvement in wettability plays a crucial role in minimising the occurrence of the balling phenomenon, which is known to have a detrimental effect on side surface roughness [ 40 ]. Wang et al [ 39 ], where the effect of a range of SLM laser powers (100–200 W) and scan speeds (600–1600 mm/s) was investigated on the roughness of Ti6Al4V parts, it was shown that increasing the laser power to the range from 180 to 200 W caused a substantial decrease of the roughness of both the upper and side surfaces of the components.…”

Numerical Simulations to Predict the Melt Pool Dynamics and Heat Transfer during Single-Track Laser Melting of Ni-Based Superalloy (CMSX-4)

“…In L-PBF, a quick scanning speed with no defects is preferred to boost manufacturing output. However, higher scanning speeds have very adverse effects on the build quality [43]. Figure 9 demonstrates how reduced scanning speeds cause the melt pool size to increase as a result of the reduction in absorption laser energy per length.…”

Titanium Alloy Implants with Lattice Structures for Mandibular Reconstruction

“…Roughness can occur in SLM constructs due to the adherence of Ti6Al4V particles to the surface, the staircase effect, and the balling effect. Due to thermal diffusion—an outcome of differences in temperature between loose particles and the solidified material—the particles can be partially melted on the surface of the construct [ 254 , 255 ]. In the staircase effect, SLM is unable to produce smooth curvatures due to the layer thickness being too large to capture the curvature, resulting in a rough surface [ 211 , 256 , 257 ].…”