SDC99钢离子氮碳共渗及稀土催渗

Plasma nitrocarburizing of SDC99 steel and rare earth catalysis

为探究SDC99冷作模具钢优化的氮碳共渗工艺,对其在不同温度、时间、气压、电压条件下的离子氮碳共渗效果开展研究。结果表明,在530℃×12 h、450~500 Pa、800~850 V、NH3/CO2为16∶1时,氮碳共渗效果较好,渗层深度为160~170μm,化合物层可达4~6μm,表面硬度为1100 HV0.3;随着稀土铈的加入,渗层深度增厚至210~220μm,化合物层可达8~10μm,其中γ’相含量由26.2%增至37.1%,表面硬度达1150 HV0.3,硬度梯度变平缓。稀土催渗样的磨损率比原始试样降低47%,耐磨性显著提高。

Plasma nitrocarburizing was carried out on SDC 99 cold working die steel at different temperature , time, pressure , voltage in a mixed gas of NH3 and CO2 with and without rare earth (RE) to obtain the optimal nitrocarburizing parameters .The results show that the optimal parameters of plasma nitrocarburizing for SDC 99 steel are of T=530 ℃, t=12 h, P=450-500 Pa, U=800-850 V and the value of NH3/CO2 =16∶1.Under this process condition , the microhardness and thickness of nitrocarburized layer are 1100 HV0.3 and 160-170 μm, respectively.Meanwhile, the thickness of compound layer is 4-6 μm.When cerium is added, the thicknesses of nitrocarburized layer and compound layer are 210-220 μm and 8-10 μm, respectively, the microhardness of compound layer is 1150 HV0.3, the mass fraction of γ′phase is increased from 26.2%to 37.1%, and the hardness gradient is gentler than that of nitrocarburized sample without RE .The wear rate of nitrocarburized specimen with RE can be decreased by 47% compared with that of untreated specimen , which shows that the wear resistance of nitrocarburized sample with RE is improved significantly .