Improvement of the surface state of additively manufactured TiAl6V4 load-bearing structures from laser powder bed fusion processes
Final Report Abstract
The project investigated the mechanical surface treatment of components from powder bed fusion laser beam melting (PBF-LB/M), a 3D printing process for the production of complex metallic components. Although PBF-LB/M enables innovative geometries, disadvantages such as high surface roughness, porosity and unfavorable stress distribution occur, which impair the service life of the components. The aim of the project was to overcome these challenges using mechanical post-processing methods - shot peening, microblasting and ultrasonic blasting. The aim was to reduce surface roughness, close pores and introduce residual compressive stresses in order to increase the load-bearing capacity of the components. A central focus was on the analysis of process-structure-property relationships, which have been little researched to date. The project also investigated how post-processing strategies and PBF-LB/M-specific properties such as porosity, microstructure and residual stresses interact. The titanium alloy Ti-Al6-V4, a material with applications in aerospace and medical technology, where high demands are placed on mechanical strength and surface quality, was used as a demonstration material. The results should promote the use of LPBF-manufactured components in safety-critical areas and increase market acceptance. As a result of the project, parameter windows for different peening angles were comprehensively characterized. This showed that the roughness scale of the additively manufactured components is best accessible for shot peening. Initial tests with a simplified geometry confirmed that the robot used was able to carry out the shot peening process precisely. Particularly noteworthy is the significant increase in fatigue strength, which was mainly achieved by shot peening, while only minor effects were observed with microblasting.
Publications
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Generalised and automated method for surface analysis of roughness and subsurface porosity using micro-computed tomography. NDT & E International, 146, 103166.
Englert, Lukas; Schulze, Volker & Dietrich, Stefan
