Impact of the scanning strategy on the mechanical behavior of 316L steel synthesized by selective laser melting

The scanning strategy is one of the most influential parameters in materials processing by additive manufacturing. Optimization of the scanning strategy is thus of primary importance for the synthesis of materials with enhanced physical and mechanical properties. Here, we examine the effect of four different scanning strategies on the microstructure and mechanical behavior of 316 L stainless steel synthesized by selective laser melting (SLM). The results indicate that the scanning strategy has negligible influence on phase formation and the type of microstructure established during SLM processing: austenite is the only phase formed and all specimens display a cellular morphology. The scanning strategy, however, considerably affects the characteristic size of cells and grains that, in turn, appears to be the main factor determining the strength under tensile loading. On the other hand, residual stresses have no apparent influence on the quasi-static mechanical properties of the samples. The material fabricated using a stripe with contour strategy displays the finest microstructure and the best combination of mechanical properties: yield strength and ultimate tensile strength are about 550 and 1010 MPa and plastic deformation exceeds 50%.