Abstract
316L stainless steel materials are widely used in impact-resistant structures. Heat treatments could affect the mechanical properties of 316L stainless steel parts formed by selective laser melting (SLM), which is vital for ensuring service safety. This study aimed to analyze the mechanical behavior of SLM 316L stainless steel under different heat treatment methods. Therefore, test specimens were prepared using the SLM technique and then annealed at 400°C for 1 h. The solution was treated at 1050°C for 20 min. The dynamic compressive mechanical properties of the deposited, annealed, and solution-treated specimens were tested at high strain rates by using a split Hopkinson pressure bar (SHPB) experimental apparatus. Moreover, the microstructures of the previously mentioned samples were analyzed by optical microscopy and scanning electron microscopy. The experimental results showed that the three-state samples exhibited strain rate sensitivity in the dynamic mechanical tests and that solution treatment could alter their mechanical properties significantly. In addition, the microstructure of the deposited specimens presented cylindrical cellular crystal features, which have a higher dislocation density. Hence, the yield strength of deposited specimens is higher than that of the solution-treated ones. After annealing, the microstructures of the samples did not change obviously, and their dynamic yield strength remained almost unchanged. After solution treatment, its cellular crystal disappeared and dislocation density dropped dramatically, resulting in a sharp decrease in yield strength. Finally, this research can provide a theoretical reference for broadening the practical application of SLM 316L material parts.
Highlights
Selective laser melting (SLM) is one of the essential technologies in the field of additive manufacturing (AM).e metal parts formed directly by the technique exhibit high dimensional accuracy, good surface quality, and almost 100% density [1,2,3]
The mechanical properties of SLM 316L stainless steel vary considerably after heat treatment methods [9, 10]. erefore, it is essential to clarify the effect of heat treatment on the dynamic mechanical properties of SLM 316L stainless steel for ensuring its service performance
334.75 507.75 558.17 606.63 deposited, annealed, and solution-treated specimens. e cellular structure can lead to substantial differences in the mechanical properties of SLM specimens, significantly increasing the yield strength. e microstructure of the deposited specimens is characterized by a honeycomb structure composed of cellular crystals, and the size of each grain is about 0.5 μm
Summary
Selective laser melting (SLM) is one of the essential technologies in the field of additive manufacturing (AM).e metal parts formed directly by the technique exhibit high dimensional accuracy, good surface quality, and almost 100% density [1,2,3]. Erefore, it is essential to clarify the effect of heat treatment on the dynamic mechanical properties of SLM 316L stainless steel for ensuring its service performance. Salman et al [11] studied the microstructure and quasistatic tensile properties of SLM 316L stainless steel at different annealing temperatures and found that tensile strength decreased with increasing temperature. Kong et al [12] researched the microstructure and mechanical properties of SLM 316L stainless steel at different solution temperatures and determined that yield strength decreased with rising temperature. Tascioglu et al [13] investigated the effects of heat treatment on the microstructure and wear behavior of SLM 316L stainless steel. Wang et al [14] compared the yield
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