Selective laser melting of 316L stainless steel: Influence of TiB2 addition on microstructure and mechanical properties

This study investigates the influence of TiB2 addition on the microstructure and mechanical properties of a 316L stainless steel synthesized by laser-based powder bed fusion process of commonly known as selective laser melting. A complex cellular microstructure with fine sub-grains, characteristic microstructure of the unreinforced 316L matrix is found in all samples. The addition of the TiB2 particles significantly reduces the size of both grains and the cells. The TiB2 particles are homogeneously dispersed in the 316L matrix and they form circular precipitates with sizes around 50-100 nm along the grain boundaries. A weak texture is formed due to addition of TiB2 particles. These microstructural features significantly strengthen the composites as-compared with the unreinforced 316L specimens. As a result of the addition of TiB2 particles, the yield strength increases from 412 +/- 7 MPa for SMC-0 to 600 +/- 3 MPa and 845 +/- 5 MPa for SMC-2.5 and SMC-5 samples, respectively.