Microstructure evolution and mechanical properties of TiB2/18Ni300 composite material produced by laser additive manufacturing

As a reinforcing phase, TiB2 exhibits exceptional wettability and stability when mixed with steel matrices, making it an ideal reinforcement for steel matrix composites. In this paper, we add TiB2 for additive manufacturing of 18Ni300 steel for weight reduction and reinforcement. TiB2 reinforced 18Ni300 matrix composites were prepared by laser cladding. SEM, EDS, and XRD were used to observe the joints' interface and fracture characteristics and analyse the substance composition. Tissue analysis was then performed using EBSD and TEM. According to the TEM and XRD results, there is a martensite structure within the cell, and the cell boundary is an austenite structure. After adding TiB2, a reinforcing phase ((Mo, Fe)3B2) is distributed at the boundary of the cell structure. The high hardness of boride increases the microhardness of the composite material. The yield strength, modulus, and elongation of the samples prepared with 18Ni300 powder are lower than that of forged 18Ni300, but the tensile strength reaches 1134 MPa. The addition of TiB2 increases the composite material's yield strength and elastic modulus significantly. This strengthening technique, which employs the addition of ceramic particles to martensitic steel, is currently not widely used. This experiment provides a theoretical basis and process reference for preparing high-stiffness and lightweight ceramic particle reinforced metal matrix composites.