Recent research led by Moritz Braun from the German Aerospace Center (DLR) and Hamburg University of Technology sheds light on the fatigue strength of additively manufactured (AM) components, particularly focusing on laser-powder bed fusion (PBF-LB/M) and wire arc additive manufacturing (WAAM). This study, published in the journal “Materials & Design,” marks a significant step in understanding how manufacturing processes impact the durability of AM parts, especially when notches or defects are present.
Additive manufacturing is increasingly being adopted across various sectors, including aerospace, automotive, and maritime industries, due to its ability to produce complex geometries and reduce material waste. However, AM components often contain process-related defects, especially near the surface. These defects can lead to premature failure under stress, a concern that has prompted further investigation into how post-treatment processes, such as machining, can enhance the fatigue strength of these components.
Braun’s research specifically addresses a gap in existing studies by examining the fatigue behavior of both plain and notched specimens produced through AM techniques, comparing them with traditional wrought stainless steel. The findings reveal that the fatigue strength of AM materials is significantly influenced by factors such as microstructure, residual stress, and the presence of notches. “PBF-LB/M specimens exhibit the highest fatigue strength in plain, notch-free conditions,” Braun noted, emphasizing the importance of microstructural differences in determining fatigue crack initiation.
Notably, the study found that when notches are introduced, the fatigue crack propagation life varies considerably among materials. PBF-LB/M specimens demonstrated shorter propagation life due to the presence of line-type defect clusters, while plain PBF-LB/M specimens were less affected, indicating that their fatigue strength is primarily determined by the initiation of cracks rather than their growth.
These insights have significant commercial implications. Industries that rely on AM components can benefit from this research by adopting post-treatment processes to enhance the performance and reliability of their products. As manufacturers seek to optimize their production techniques and improve the longevity of AM parts, understanding the relationship between manufacturing methods and fatigue strength becomes crucial.
The findings from this study not only advance the scientific understanding of AM materials but also pave the way for improved practices in sectors where safety and performance are paramount. By addressing the challenges posed by microstructural defects and investigating the effects of notches, companies can better harness the potential of additive manufacturing technologies. As Braun concludes, the research highlights the need for continued exploration into the fatigue strength of AM components, particularly in the context of post-production treatments.
