Research On Corrosion And Fatigue Properties Of 0Cr21Mn17Mo2N0.8 Austenitic Stainless Steel

With the development of society and the progress of science and technology,all walks of life are demanding more and more for materials,and the appearance of high nitrogen nickel free austenitic stainless steel conforms to the demanding.It has higher strength and corrosion resistance than the traditional austenitic stainless steel,meanwhile maintaining the original high plasticity,toughness and no magnetic properties.In addition,the complete substitution of nitrogen for nickel saves greatly scarce and expensive nickel resources and reduces production costs.Although the high nitrogen nickel free austenitic stainless steel has excellent mechanical properties and corrosion resistance,it often suffers from fatigue failure due to the action of load in the process of use.Therefore,the study of fatigue performance is crucial.Taking 0Cr21Mn17Mo2N0.8 new-type high nitrogen austenitic stainless steel as the research object,the mechanical properties and corrosion resistance of the forging and solid solution alloys were compared and analyzed.The tensile strength,yield strength and elongation of the tested alloy were tested by an electronic universal testing machine,and its impact toughness was tested by a pendulum impact testing machine.The corrosion resistance of the alloy to sea water was analyzed by a salt spray corrosion chamber,and the corrosion resistance mechanism of high-nitrogen austenitic stainless steel was summarized.High cycle fatigue test was carried out with high frequency fatigue testing machine.Scanning electron microscopy?SEM?and transmission electron microscopy?TEM?were used to analyze the fatigue fracture.The microcosmic mechanism of fatigue crack initiation and propagation was discussed.The fatigue fracture mechanism was analyzed.The research results show that:?1?Tensile and impact tests at room temperature show that both alloys have high strength and high plasticity.In addition,?_0.2 is 883.1MPa,?is 47.6%,A_k is 90.06J for forged alloys,and?_0.2 is 764.7MPa,?is 65.3%,A_k is 188.90J for solid solution alloy.The strength of forged alloy is higher than that of solid solution alloy,and the solid solution alloy shows excellent toughness.?2?Salt spray experiments show that the solid solution alloy shows better corrosion resistance.The corrosion rate of the forged alloy was 3.64×10^-6g/cm²·h,and that of the solid solution alloy was 3.47×10^-7g/cm²·h.The corrosion rate of solid solution alloys is one order of magnitude lower than that of forged alloys.?3?In the condition of stress ratio R=0.1,the conditional fatigue strength of forged alloy is 865.25MPa,and that of solid solution alloy is 736.10MPa.The results of fracture observation show that the fatigue source of forged alloy is precipitate or inclusion,while the fatigue source of solid solution alloy is uneven stress distribution at the edge of sample.Because the toughness of the solid solution alloy is better,the grain boundary has a stronger hindrance to crack propagation.Because of its high strength,the fatigue life of forged alloy is higher than that of solid solution alloy.However,forged alloys are more prone to sudden failure,while solid solution alloys are more stable.