Abstract: The microstructure and properties of the nitrocarburized layer are greatly affected by the nitriding potential and carbon potential in the atmosphere which can be directly controlled by the flow rate of NH3 and CO during nitrocarburizing. The effects of NH3 and CO flow on the microstructure and properties of the compound layer were investigated by scanning electron microscopy, X-ray diffractometer, microhardness tester and electrochemical analyzer. The results show that the thickness and porosity of the compound layer increases with the increasing NH3 flow du-ring gas nitrocarburizing. With the rising of CO flow, the compound layer becomes more compact, but the thickness of the compound layer increases first and then decreases. The addition of C in the nitrocarburized layer can restrain the formation of γ′ phase forming and promote the formation of ε phase. While the excess C would result in the emerging of θ phase. Fortunately, the permeated C show limited impact on the corrosion behavior of the compound layer. The combined effects of NH3 and CO on nitrocarburized layers can be realized through raising the flow rate of NH3 and the corresponding flow rate of CO appropriately, thus a thicker and compact compound layer with good corrosion-resistance can be formed successfully.
徐强, 洪悦, 李楠, 伍翠兰. 气体氮碳共渗中NH3和CO流量对低碳钢渗层组织及其性能的影响[J]. 材料导报, 2019, 33(2): 330-334.
XU Qiang, HONG Yue, LI Nan, WU Cuilan. Effect of NH3 and CO Flow of Gas Nitrocarburizing on Microstructure and Properties of Nitrocarburized Layers of Low-carbon Steel. Materials Reports, 2019, 33(2): 330-334.
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2019, Vol. 33 
