Laser sintering of metal powders: failure analysis and implementation of solutions for aluminium and stainless steel parts

Abstract

In this research, the failures and possible solutions of direct metal laser sintering (DMLS) have been investigated, with the aim of presenting an overview of the current state of science and possible technical solutions to the various challenges and potential solutions. DMLS technology allows to produce high density parts and has proven to be suitable for the cost-effective production of both mass-produced and individual parts in the automotive, aerospace, medical and hydrogen technology industries. This study reveals the fundamental principles, potential benefits, and limitations of metal 3D printing. The defects are categorized into those related to raw materials and those caused by the manufacturing process. The properties of the parts fabricated by this method are mainly depending on the quality of the raw material and the intensity of the laser beam. Clusters of raw materials have a negative impact on the whole manufacturing process, requiring their investigation and avoidance. Another critical defect identified is the significant internal stress generated during the manufacturing process. Various methods are developed to quantify and mitigate these internal stresses. This study provides a detailed analysis of these defects and their impacts, along with a review of literature-based solutions. Among the evaluated and implemented solutions, emphasis is placed on the effects of preheating the build plate and post-process heat treatment. Future objectives and research directions are proposed, presenting and assessing alternative solutions such as Vibratory Stress Relief (VSR) and Thermo-Vibratory Stress Relief (TVSR), which combine heat treatment with vibration. In the scope of the research, the process by which the most common failures occur, and their potential outcomes was reviewed. Special attention was given to deformation caused by internal stress and the possibilities for its mitigation. The feasibility of applying a new approach was investigated, and future research objectives were outlined. SEM imaging was employed to conduct and analyse the grain size of stainless-steel raw material, and agglomerates were observed in the post-print recycled powder.