Experimental characterization and micromechanical-statistical modeling of 316L stainless steel processed by selective laser melting

摘要

Additive manufacturing (AM) is regarded as one of the breakthrough innovations since the 19th century, whose impact on the manufacturing world is recognized as the same with the impact of airplane on the transportation industry [1]. Selective laser melting (SLM), one of the most popular AM techniques for processing metallic materials, has demonstrated its great potentials in medical, aerospace and automotive applications. The SLM technique itself is a complex metallurgical process, involving multi-physics phenomenon in laser scanning, powder melting and bonding procedure. Such a process may introduce a variety of defects and flaws such as pores and cracks, significantly reducing the mechanical performance of the final products. In this paper, we present experimental studies and micromechanical modeling to investigate the effects of the internal pores on the mechanical properties of 316L stainless steel (SS316L) processed by the SLM technique. Specifically, the internal pore characteristics such as size, morphology, spatial distribution and porosity (defined as the total volume of the pores divided by the total volume of the material) of the SLM processed SS316L is experimentally characterized and correlated with the mechanical properties. More importantly, a micromechanical model taking into account the statistical pore characteristics from the XCT analysis is developed to predict the elastic properties of the SS316L product. The numerical prediction results show good agreement with two analytical models and the experimental characterization of the mechanical properties. The present study provides future designers a methodology in predicting the mechanical properties using the XCT analysis results, which is a promising possibility of saving the expensive cost on destructive testing.