稀土元素对38CrMoAl钢离子渗氮工艺的影响

目的缩短38CrMoAl钢离子渗氮工艺周期。方法在离子渗氮过程中,添加稀土金属镧(La)及稀土镧铈合金(La-Ce)。通过显微硬度仪、光学金相显微镜、扫描电镜及能谱分析仪对于离子氮化层的表面硬度、脆性、微观显微组织、稀土元素含量进行检测分析,并和常规离子渗氮工艺进行对比研究。结果在离子渗氮工艺过程中,添加稀土金属镧(La)及镧铈合金(La-Ce)后,氮化层表面硬度提高约130～200 HV,渗氮速度提高了15%～30%,氮化周期显著缩短。稀土催渗离子渗氮层的脆性均为Ⅰ级,比常规离子渗氮更优异。同时,稀土元素的渗入细化了晶粒,使得渗层氮化物组织致密、呈弥散分布,优化了氮化层的相结构组成。结论稀土元素的加入可以有效提高渗氮层的表面硬度和脆性等级,改善了氮化层性能。同时缩短了离子渗氮工艺周期。

Effects of Rare Earth Elements on Ionic Nitriding Process for 38CrMoAl Steel

Objective To shorten the ionic nitriding process cycle of 38CrMoAl steel. Methods In the process of ion nitriding, the rare-earth metal Lanthanum and the rare-earth La-Ce alloy was added to ion nitriding furnace. Then the surface hardness, brittleness, microstructure, of the rare earth elements of the ion nitriding layer was detected and analyzed by microhardness instrument, optical metallographic microscope, scanning electron microscope and energy spectrum analyzer, and it wasthen compared with the conventional ion nitriding process. Results The ion nitriding process catalyzed by rare earth (La and La-Ce) can could not only increase the surface hardness of the ion nitriding layer by 130~-200 HV, but also increase the nitriding speed by 15%~%-30%, and shorten the ionic nitriding process cycle was shortened significantly. The brittleness of the rare earth nitriding layer is was grade I grade, which is was better than that of the conventional nitriding layer. In addition, the infiltration of rare earth element can refine the grain structure , making make the nitride structure dense and distributed in a state of dispersion, andalso, optimize optimize the phase structure of the ion nitriding layer. Conclusion The addition of rare earth elements can effectively improve the surface hardness and brittleness of the ion nitriding layer, improve the performance of the ion nitriding layer, and shorten the ionic nitriding process cycle of 38CrMoAl steel.