Precise control of low-pressure vacuum carbonitriding in shallow layers of 16Cr<SUB align="right">3NiWMoVNbE steel

As a commonly employed carburising gear steel, 16Cr3NiWMoVNbE steel has received relatively limited research attention in the context of shallow carbonitriding. Traditional controlled atmosphere carbonitriding (CACN) struggles to achieve precise control over the thickness of shallow layers, ensure consistent high-quality layers, and exhibits a steep carbon concentration gradient, restricting its application in high-performance aerospace gears. In this study, we conducted a comparative analysis of CACN and low-pressure vacuum carbonitriding (LPCN) technologies, investigating their effects on the characteristics of the diffusion layer. Research findings indicate that LPCN can achieve finely dispersed carbides on the material's surface and exhibits a gentle hardness gradient transition from the carbonitrided layer into the substrate with increasing depth. Moreover, LPCN can accurately control the depth of the diffusion layer within 0.35 mm, thereby demonstrating superior carbonitriding quality control and diffusion layer thickness management under shallow layer conditions compared to CACN technology.