Study On The Effects Of Solid Nitriding Of304Stainless Steel With Electric Pulse Treatment

It was studied the impact of pulsed electric field on the nitride layer of stainless steel.The effective nitrided case depth of the stainless steel was studied by the use of box furnacesolid tufftriding process, electric impulse nitriding, the Zeiss Axiovert200MATmetallographic microscope, microhardness tester, scanning electron microscopy and energydispersive analysis. The experimental results show that:With the increase of the pulse frequency, the thickness of the nitride layer gets thicker.When the impulse frequency reaches9Hz, the thickness of the nitride layer reaches170μm.But when the frequency is increased to12Hz, the diffusion layer thickness decreased to80μm. The reserch shows that within the scope of this experiment,9Hz is the best parameterswhen the other conditions are fixed. The thickness of the nitride layer also gets thicker withthe increase of the pulse voltage. And the nitride layer reaches170μm when the pulse voltageis8KV.Starting pulse after insulation for1hour at550℃, the nitrided layer is the thickest. In acertain time, treating time is proportional to the layer thickness. While as the interval of pulsetreatment is longer, the thickness of the nitrided layer gets thinner. That is to say the longer ofthe pulse time the deeper of the permeability nitrogen layer thickness. But when the samplesprocessed by excessive continuous pulse processing, the effect is opposite.Different electrode connecting format have an effect on the thickness of nitrided case.Along with the furnace cooling, the nitride surface is neat and clear and there are no signs ofdenitrification.With the changes of the ingredient of nitridation carrier, the thickness of the nitrided caseis different. In this paper, the best carrier combination is consist of sawdust, ammoniumchloride and sodium carbonate.The content of the yellow prussiate and carbamide in the nitriding agent effects thenitriding layer thickness of the stainless steel. In this paper, without electrical pulseprocessing120g yellow prussiate and60g carbamide can get thicker nitriding layer. Thethickness of the nitriding layer can reach180μm with electrical pulse treatment when thecontent of the yellow prussiate is180g with no carbamide.In the process of nitriding, Iodine is the catalyst. The deepest nitriding layer can reach180μm when the content of Iodine is2g. While, the nitriding layer did not increasesignificantly as the Iodine is3g.Above all, the thickness and microhardness of the nitriding layer is thicker and higherafter the electric pulse than that without electrical pulse treatment.