高精度细长管零件内壁防腐研究

AbstractAbstractQPQ salt bath compound processing technology (also known as QPQ tech-nology),in recent years as a new type of surface strengthening technology.The technology relative to the traditional surface strengthening process such as:nit-riding,softnitriding,chrome,high-frequency quenching,etc,with outstanding wear resistanceand corrosion resistance.It is widely used in the automotive industry,mold,agricultural machinery,military firearms and other fields.In this paper,50B steel was used as the research material and chrome-plat-edsample as the control sample.The effects of different nitriding time on the morphology and corrosion resistance of the infiltration were investigated by QPQ treatmentwith different nitriding time (2h,3h,4h).The hardness gradient,phase composition,microstructure and element composition of the modified 50 steel surface were analyzed by Metallographic microscope,Vickers micro hardness tester,X-ray diffraction(XRD),scanning electron microscopy (SEM),energydispersive spectrometer (EDS).At the same time,the influence of QPQ processand chrome plating process on its properties was studied by wear experiment and electrochemical experiment.The results of the study show that the infiltration layer after 50B steel QPQ treatmentis divided into:oxide layer,loose layer and compound layer.The oxide layer is mainlycomposed of Fe304.This layer has a great impact on the improvement of corrosionresistance and abrasion resistance;The compound layer is composed of Fe3N and Fe4N,and the compound layer is getting thicker as the nitriding time increases;And the looselayer is a mixed phase of several kinds,is a layer of porous area,the layer has a significantimpact on corrosion resistance with the increase in nitriding time,more and more serious