关键词: 真空碳氮共渗, 淬火, 45钢, 气体流量, 硬度均匀性

Abstract: By controlling the atmosphere flow rate and quenching temperature, a carbonitriding heat treatment test was conducted on 45 steel, followed by surface hardness, microstructure examination, and effective hardened layer depth analysis. The results show that under the carbonitriding heat treatment process with nitrogen, acetylene, and ammonia flow rates of 56, 56, and 38 L/min, respectively, and carbonitriding at 880 ℃ and quenching at 800 ℃, the surface microstructure of the 45 steel consists of acicular martensite, a small amount of carbonitride-containing retained austenite, and carbonitride compounds, while the core microstructure is composed of low-carbon martensite and proeutectoid ferrite. The surface hardness uniformity is improved, and the effective hardened layer depth is approximately 0.60 mm.

Key words: vacuum carbonitriding, quenching, 45 steel, gas flow rate, hardness uniformity