| Austenitic stainless steel has excellent corrosion resistance,but its low hardness and poor wear resistance restrict its usage as transmission moving parts in industrial application.It was firstly analyzed for the coal washing sieve plate and paper-making sieve plate products in this paper,the results showed that the stainless steel sieve suffered from the erosion and abrasion of solid medium when washing work.On the surface of stainless steel sieve,pits resulted from abrasion and corrosion were found,which make the workpiece under service disabled early and cause the increase of production cost.Gaseous nitriding can improve the surface hardness of stainless steel,contributing further improvement to the wear resistance of stainless steel.AISI 304 and AISI 316 austenitic stainless steel have been chosen to be nitrided.The nitrogen diffusion rate was accelerated by using the method of gas catalytic in-situ nitriding and the nitriding layer with a certain thickness was obtained.The microstructure,composition,morphology and phase of the samples were analyzed by electron probe microanalyser(EPMA),field emission scanning electron microscopy(FESEM)and X-ray diffraction instrument(XRD).The friction coefficient,wear rate and wear topography of nitriding layer were characterized by using microhardness tester,friction and wear testing machine,and 3D profilometer.Besides,the reciprocating linear dry friction and failured wear mechanisms of nitriding layer are also discussed.According to the different requirements of wear-resistant and corrosion-resistant working conditions of stainless steel products,two kinds of processing technology for anti-corrosion nitriding(430?)and anti-wear nitriding(560?)were chosen to treat the stainless steel.Research shows that the layer of compact S-phase,with a thickness of 10?m,hardness of 1000HV,has been formed when nitriding temperature is 430?.This phase has good properties of abrasion resistance and corrosion resistance and lower corrosion current density of 1.25 X 10-6A/cm2 compared to that of 1.15 × 10-5A/cm2 of the substrate as well as more positive corrosion potential of-0.37V compared to that of-0.45 V of the substrate.With nitriding temperature increasing to 560?,wear-resisting performance of sample improved due to the formation of CrN owning a high hardness value beyond 1200HV,but with decreased corrosion resistant performance,and the corrosion current is bigger,the corrosion potential is negative.Considering the factory usage of stainless steel sieve plate in washing work condition,different loads(10N,30N,50N)were chose for matrix,corrosion-resistant nitriding(430?)and wear-resistant nitriding(560?)in linear dry friction and wear experiments,analyzing the load on friction and wear mechanism of nitrided specimens.The results showed that serious adhesion and abrasive wear happened on the surface of the matrix,and the values of wear rate and wear rate were 1.4 mm3,6.48x10-4 mm3/m N under the condition of load of 30N and duration of 2h.Slight abrasive wear was the main worn mechanism of 430?nitrided samples,and the wear volume and wear rate were one half of that of the matrix sample with value of 1.4 mm3,6.48×10-4 mm3/m·N.The wear volume and wear rate of the wear-resistant nitriding samples were further reduced to a third of that of the matrix sample,and the wear resistance was better than that of the corrosion-resistant nitrided samples. |
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