预氧化+稀土铈对42CrMo钢离子渗氮的影响

针对离子渗氮渗层浅及生产周期长等技术难题,采用预氧化与稀土复合催渗对工程常用结构钢42CrMo进行了离子渗氮。利用显微硬度计、光学显微镜(OM)、扫描电镜(SEM)等对渗氮速率、渗氮层组织、表面形貌等进行了系统的研究。结果表明,经400 ℃×1 h氧化+0.6 cm²/kg(铈表面积/装炉量)稀土的复合催渗工艺具有最佳催渗效果;与无催渗试样相比,优化后的复合催渗不仅提高了渗氮效率,同时减少了脉状氮化物,且降低了渗氮层的硬度梯度。

Effect of pre-oxidation and rare earth cerium on plasma nitriding of 42CrMo steel

To solve the technical problems such as shallow nitrided layer and long production cycle, the commonly used structural steel 42CrMo was plasma nitrided by pre-oxidation and rare earth complex activated nitriding. The nitriding rate, the microstructure of the nitrided layer and surface morphologies were studied systematically by using microhardness tester, optical microscope (OM), and scanning electron microscope (SEM). The results show that the best nitriding effect can be realized by pre-oxidation at 400 ℃ for 1 h+complex activated nitriding process with 0.6 cm²/kg(cerium surface area/charging weight). Compared with that without activated nitriding, the optimized complex activated nitriding not only improves the nitriding efficiency but also eliminates vein-like nitride, reduces the hardness gradient of the nitrided layer.