Effect of high laser scanning speed on microstructure and mechanical properties of additively manufactured 316L

Abstract

AbstractDue to its ease of processing, the stainless steel 316L is a widely used material for the laser powder bed fusion (PBF-LB/M) process. Compared to other additive manufacturing technologies PBF-LB/M has a lot of advantages such as design freedom and high resolution of details. However, PBF-LB/M also has some disadvantages, such as a reduced build-up rate. In general, 316L provides a wide range of parameter settings used for PBF-LB/M. In this study, the manufacturing limits were approached allowing a maximum build-up rate along with a high relative density > 99% without compromising the required mechanical properties. Microstructure analyses as well as tensile tests were performed to validate this approach. This article also provides insights on defects and relative density for scanning speed above 3000 mm/s. Furthermore, it was shown that the scanning speed has a major influence on the grain size and on the texture of the specimens. For the first time, the relative density, microstructure and mechanical properties of additively manufactured 316L were determined in relation to each other for high scanning speed. A set of parameters has been found that works best with a laser power of 285 W and a scanning speed of 1250 mm/s which results in a specimen relative density of 99.2%, a yield strength of 425 MPa, a tensile strength of 586 MPa and a build-up rate of 4.64 mm3/s. The findings can be further used to enhance the mechanical properties of PBF-LB/M 316L in terms of high build-up rates.