镧对38CrMoAl钢氮化层组织和抗冲蚀磨损性能的影响

Effect of Rare Earth Element Lanthanum on the Microstructure and Erosion Resistance of Nitrided Layer on 38CrMoAl Steel

考察了在气体氮化渗剂中加入微量镧元素对 38Cr Mo Al钢氮化层组织、韧性及抗冲蚀磨损性能的影响 .试验结果表明 ,含镧的氮化层的韧性和抗冲蚀磨损性能明显优于普通氮化层 .这是由于镧在氮化时渗入到钢表层并发生微合金化 ,从而改善渗层的组织所致 .采用扫描电子显微镜对冲蚀磨损试样表面形貌进行观察发现 ,普通氮化层的磨损机理为塑性变形及犁沟剥落 ,并伴随着横向裂纹的萌生和大块磨屑的剥落 ;而含镧的氮化层的磨损机理为塑性变形及犁沟剥落 .

Nitrided layer was prepared on 38CrMoAl steel surface by using ammonia gas as the nitriding medium in a gas nitriding oven. The effect of rare earth La doping on the microstructure, toughness and erosion resistance of the nitrided layers was ionvestigated by means of optical microscopy, scanning electron microscopy, transmission electron microscopy, and erosion wear testing. The results show that rare earth element La helps to improve the microstructure of nitrided layers by way of micro alloying effect which is dependent on its permeation into the nitrided layers. Subsequently the toughness and erosion resistance of La nitrided layer are increased significantly as compared with the conventional nitrided layer. The erosion wear of conventional nitrided layer is characteristic of plate like peeling and plastic deformation, accompanied with cross cracks and peeling of larger wear debris, that of nitrided layer containing La is dominant by plate like peeling and plastic deformation.