Effect of TiB₂ Content on Microstructure and Properties of TiB₂/4Cr13 Steel Composites by Selective Laser Melting Forming Based on PLC Control

TiB₂/4Cr13 steel composites with different mass fractions (0.6%, 1.2%, 1.8%) of TiB₂ were prepared by mechanical ball milling and selective laser melting forming, and the effects of TiB₂ content on the phase composition, microstructure, hardness, wear resistance and corrosion resistance of the composites were studied. The results show that the composite contained α-Fe, γ-Fe and TiB₂ phases. With the increase of TiB₂ content, the relative density of the composite decreased. When the mass fraction of TiB₂ was 0.6%, the microstructure of the composite was the most fine and uniform. With the increase of the content of TiB₂, the grain size increased, and cracks, micropores and other defects appeared in the microstructure. With the increase of TiB₂ content, the hardness of the composites decreased, the friction coefficient and wear rate increased, the pitting and free-corrosion potential decreased, and the free-corrosion current density increased, indicating that the corrosion resistance decreased.