Reasearch Of Low Temperature Ion-acetylene Gas Hardening Treatment Of Aisi316l Austenitic Stainless Steel

In this paper,the AISI316 L austenitic stainless steel is treated by low temperature ion-acetylene gas hardening treatment technology,the changes of thickness,surface hardness,hardness gradient,phase structure,wear resistance and corrosion resistance of the hardened layer are studied.In this paper,adopting low-temperature ionacetylene gas hardening treatment process,First,using ion bombardment the surface of stainless steel to remove the passive film,and then carburizing treatment.Successfully solves the temperature control and non-uniform temperature of the single plasma hardening treatment and the pollution of equipment and environmental of low-temperature gas hardening treatment.In order to ensure the activity of carburizing gas,this study uses C₂H₂ as the carburizing gas,because of its strong supply of carbon,and the decomposition of C₂H₂ will occur only when it is in contact with the steel surface,release of the active carbon atoms,so it formed less carbon black in the furnace when carburizing prosess.In this paper,the effect of carburizing temperature,carburizing holding time and carburizing gas ratio on the low temperature ion-acetylene gas hardening treatment of AISI316 L austenitic stainless steel were studied.The results showed that the critical temperature of the low-temperature ion-acetylene gas hardening without carbide precipitation was 540?.If above this temperature,carbides such as Cr₂₃C₆,Cr₇C₃,CrC,Fe₃C,Fe₂C,were precipitated in the carburized layer,resulting in the decrease of corrosion resistance of the stainless steel surface.With the extension of the holding time,the thickness and hardness of the carburized layer increaseed from fast to slow.When the gas ratio was H₂: C₂H₂ = 3: 1,the carburized layer thickness and hardness reached the maximum.In this paper,adopting orthogonal test studied the relationship between H₂: C₂H₂,ion bombardment time and carburizing pressure factor on the thickness and hardness of carburized layer.Finally,the optimum parameters were obtained as follows: carburizing temperature 520 ?,gas ratio H₂: C₂H₂ = 1: 1,carburizing pressure-0.02 MPa,ion bombardment time 20 min.In this paper,the carburized layer after carburizing with two kinds of C₂H₂ and CO gas was also compared.The results showed that all obtain a hardening layer of uniform white bright after carburizing with these two gases,but the thickness,surface hardness and corrosion resistance of carburizing layer after the treatment of C₂H₂ were higher than that of CO.