Synergy Effect of Abrasive Blasting and Large-area EB Irradiation on Surface Finishing of AMed Titanium Alloy

Abstract

Among a broad spectrum of AM technologies, electron beam melting (EBM) is widely applied in AM process for producing titanium alloy parts. In general, AMed metal products have very rough surface of more than 200µmRz, since relatively large beads are arranged on their surface by scanning electron beam. Moreover, surface irregularities such as spatter and cavity are also generated on the surface. Rough surface and surface irregularities would lead to reduction in surface strength and poor appearance. Therefore, post surface finishing processes are required to smooth the surface of AMed metal products. One of the common surface smoothing processes is abrasive blasting. Large surface roughness can be decreased by abrasive blasting, and compressive residual stress can be introduced to the surface. However, there is a limitation to reduction of surface roughness. On the other hand, in large-area electron beam (large-area EB, LEB) irradiation method developed recently, mold steel surface can be finished by melting it in a few minutes. However, it is not easy to smooth surface with large initial surface roughness, and a tensile residual stress may be generated on the surface.In this paper, surface smoothing of AMed titanium alloy by combination of abrasive blasting and large-area EB irradiation was proposed. At first, the AMed titanium alloy surface was blasted to reduce the initial large surface roughness to some extent and change the surface topography. Then, large-area EB was irradiated to the blasted surface. It is made clear that surface roughness significantly decreases when large-area EB is irradiated to the blasted surface with small mean width. Moreover, tensile residual stress generated in large-area EB irradiation can be reduced by abrasive blasting. Therefore, combination of abrasive blasting and large-area EB irradiation is effective for efficient reduction of large surface roughness of AMed titanium alloy.