Effect of nano TiC on microstructure and microhardness of composite additive manufacturing 316L stainless steel

Abstract

The lower surface hardness limits the further application of 316 L stainless steel. In this study, selective laser melting (SLM)/laser metal deposition (LMD) composite additive manufacturing technology was used to prepare five kinds of 316L-nano-TiC cermet strengthening layers on the surface of 316L stainless steel, and to study the effect of nano-TiC particle content on the microstructure and the influence of microhardness. Use Laser microscope, scanning electron microscope (SEM), X-ray diffractometer (XRD) to analyze the structure, element distribution and phase composition of the strengthening layer. The hardness of the strengthened layer was analyzed using a Vickers micro-hardness tester. The study found that the composite SLM/LMD formed samples changed continuously from LMD forming to SLM forming, showing good metallurgical bonding. Diffusion of TiC particles was observed in the SLM strengthening layer, and TiC phase was detected in the strengthening layer. Compared with the 316L matrix, the microhardness of the strengthened layer is significantly improved. When 50wt% TiC is added, the average hardness of the strengthened layer is 1.9 times that of the 316L matrix, and the highest is 408.9HV. The results of this study show that the strengthening layer manufactured by composite additive materials can effectively improve the hardness of the 316L stainless steel matrix. As the content of nano-TiC in the preset powder increases, the microhardness of the strengthening layer first increases and then decreases, and the hardness of the 50wt% TiC strengthening layer is the highest. There are distributed nano-TiC particles in the structure of the strengthening layer, and the distribution of nano-TiC particles in the 50wt% TiC strengthening layer is more uniform than other samples. This research provides a new reference for the strengthening of 316L stainless steel through SLM/LMD composite additive manufacturing technology and the addition of nano-TiC particles.

Nano TiC particles modulate wear resistance and impact toughness of 40Cr alloy steel gradient-reinforced layer fabricated by laser melting deposition

“…Due to the mismatch between the thermal physical properties of the TiC reinforced phase and the 12CrNi2 alloy steel, thermal stress will be generated during the preparation process and cracks are likely to occur [22,23], so this study developed a nano-TiC gradient reinforced layer. In previous studies of functional enhancement layers, researchers focused on improving single material properties [24,25], while gears needed to improve wear resistance and impact toughness. In order to further understand the strengthening mechanism of the gradient reinforced layer, the nano-TiC gradient reinforced layer was developed in this study, and the wear resistance and impact toughness tests were carried out, which provided a reference for the development of the gradient reinforced layer with both wear resistance and impact toughness.…”