Research On Surface Modification Of Carbon Steel By Pulse Detonation-plasma Technology

Pulse detonation-plasma technology（PDP）is a new technique for the comprehensive application of explosive and high-energy beam processing in the field of surface modification.In this paper,first at al,the PDP treatment of 45 steel with low and high tempering after quenching and T10 steel with low tempering after quenching was carried out by changing the distance H between nozzle and the surface of workpiece respectively.The effect of distance H on the surface and cross-sectional morphology,phase structure and surface micro-hardness of the samples before and after PDP treatment were analyzed by using optical metal ographic microscope（OM）,field emission-environment scanning electron microscope（SEM）,X-ray diffract io n（XRD）and micro-Vickers hardness tester.And the influence of the heat treatment state of the 45 steel substrate on the PDP treated modified layer was discussed.On this basis,the 45 steel,T8 steel and T10 steel were subjected to PDP treatment with optimized treatment distance and other same parameter.OM,SEM,XRD,micro Vickers hardness tester,friction and wear test and electrochemical corrosion were used to analyzed the influence of carbon content on the microstructure and properties of the modified layer after PDP treatment.The results show that:（1）Remelting and the grain structure refined occur on the surface after PDP treatment to obtain a double-layer structure modified coating consisting of a like-columnar region of the surface layer and a microstructure refinement region of the subsurface layer.The new austenite phaseγ-Fe and Fe₃N phases is formed after PDP treatment.As the processing distance increasing,the thickness of the modified layer increases.（2）PDP treatment significantly increases the hardness of the surface layer of the all samples.When H≦50 mm,the hardness of the modified layer increases first and then decreases with increasing depth from the surface;When H>50 mm,the hardness of the modified layer decreases rapidly with increasing depth from the surface.The increase of carbon content is favorable to increase hardness.（3）The PDP surface treatment can effectively improve the friction and wear resistance of all the samples,and the increase of carbon content is more effective in improving the wear resistance.Under the same conditions,the corrosion resistance of the modified layer after PDP treatment is slightly reduced,and the modified layer obtained from the low carbon content material has a more pronounced reduction in corrosion resistance.（4）The comprehensive analysis of the microstructure and properties of the modified layer shows that the optimized process distance is H=50 mm,the heat treatment state of the substrate has little effect on the modified layer,and PDP treatment will have a more pronounced effect on the surface modification of materials with high carbon content.