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Study On Microstructure And Property Of Austenitic Stainless Steel Treated By Plasma Nitriding And Plasma Nitriding/CrN Coating

Posted on:2019-05-04Degree:MasterType:Thesis
Country:ChinaCandidate:Q C HuFull Text:PDF
GTID:2321330569478281Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
In order to improve the wear resistance of ball valve which is made of austenitic stainless steel,we utilized Plasma Nitriding technology and Physical Vapour Deposition(PVD)technology to prepare nitriding layer and nitriding-layer/CrN multilayer coatings,the temperature of nitriding process were 400?,440? and480?.The surface morphology,cross-section morphology and components of austenitic stainless steel which treated by plasma nitriding or plasma nitriding/CrN coating duplex treatment were analysied by scanning electron microscope(SEM),energy dispersive spectrometer(EDS),optical microscope(OM)and X-ray diffraction(XRD).The microhardness,wear resistance and corrosion resistance of austenitic stainless steel which treated by pla sma nitriding or plasma nitriding/CrN coating duplex treatment were tested by Vickers hardness tester,the material surface tester(HSR-2M)and electrochemical workstation.The results show:(1)The temperature of plasma nitriding has an important impact on nit riding layer.316 stainless steel treated by plasma nitriding at 400? obtained the thinnest nitriding layer and exhibited the worst wear resistance as well as the best corrosion resistance.316 stainless steel treated by plasma nitriding at 480? obtained the thickest nitriding layer and exhibited the worst corrosion resistance as well as the best wear resistance.(2)Compare the 316 stainless steel treated by plasma nitriding/CrN coating duplex treatment.The sample treated by plasma nitriding at 400?/CrN coating duplex treatment exhibited the best corrosion resistance and the worst wear resistance;the sample treated by plasma nitriding at 480?/CrN coating duplex treatment exhibited the worst corrosion resistance and the best wear resistance.This phenomenon illustrated that nitriding layer influence the wear resistance and corrosion resistance of multilayer coatings.(3)Based on plasma nitriding applied to austenitic stainless steel,CrN coating can improve the wear resistance further.At the same time,CrN coating c an improve the corrosion resistance of the 316 stainless steel treated by plasma nitriding at 440? and 480?.(4)Low temperature(400?)plasma nitriding and plasma nitriding/CrN coating duplex treatment applied to austenitic stainless steel can improve the w ear resistance of austenitic stainless steel on the basis of minimizing the effect on corrosion resistance.
Keywords/Search Tags:austenitic stainless steel, plasma nitriding, PVD, CrN coating, wear resistance, corrosion resistance
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