Recent advancements in laser powder bed fusion (LPBF) technology have the potential to revolutionize the repair of complex components, particularly in the aerospace sector. A study led by Zhu Jiarui from the School of Materials Science and Engineering at the University of Science and Technology Beijing sheds light on the intricate processes involved in repairing directional DZ125 alloy, a material often used in high-performance aero-engine blades.
LPBF technology stands out for its flexibility and rapid manufacturing capabilities, making it an ideal choice for precision repairs. However, understanding the evolution of defects and microstructures during the LPBF process has proven challenging when relying solely on experimental methods. To address this, Zhu and his team employed a combination of finite volume methods and cellular automaton models to simulate the behavior of the powder bed melt pool and the subsequent microstructure formation.
“The insights gained from our simulations reveal critical relationships between energy density and defect formation,” Zhu explained. He noted that when energy density falls below 87.9 J/mm³, it leads to incomplete melting of powder particles, resulting in defects such as pores and unmelted areas. Conversely, energy densities exceeding 137.4 J/mm³ can compromise the smoothness of the solidified melt pool, introducing new challenges in the repair process.
The research highlights a significant finding: as laser power increases, the temperature gradient within the melt pool decreases, promoting the formation of new crystal nuclei. Zhu stated, “Our findings indicate that transitioning from columnar crystals to a predominance of polycrystalline grains occurs as laser power is ramped up from 150 W to 250 W.” This transformation is crucial, as it directly influences the mechanical properties of the repaired components.
By identifying optimal process parameters—specifically, a laser power of 200 W, a scanning speed of 1000 mm/s, and a layer height of 65 μm—the study not only aids in reducing experimental costs but also accelerates the development of efficient repair techniques for alloys. These advancements are expected to have a substantial commercial impact, particularly in industries where the reliability and longevity of components are paramount.
As the construction sector increasingly adopts advanced manufacturing technologies, the implications of this research extend beyond aerospace. The ability to repair critical components with precision can enhance the durability and performance of various structures, potentially leading to significant cost savings and reduced downtime.
This groundbreaking research was published in ‘Cailiao gongcheng,’ which translates to ‘Materials Engineering,’ underscoring its importance in the field. For more insights into Zhu Jiarui’s work and the future of LPBF in construction, you can visit the University of Science and Technology Beijing. The findings from this study could pave the way for innovative repair solutions that not only improve performance but also contribute to sustainable practices in construction and manufacturing.
