Study On Hydrogen Embrittlement Susceptibility Of A TRIP-Assisted Duplex Stainless Steel

Based on the alloy composition of traditional duplex stainless steel,an economical duplex stainless steel with low austenitic stability was developed by replacing expensive Ni with Mn and N elements.In the plastic deformation process,metastable austenite spontaneous martensitic transformation,greatly improve the plasticity and strength(TRIP),so it is also called TRIP duplex stainless steel.It has a broad application prospect in rail transit,petrochemical and other fields.However,in the process of manufacturing(such as pickling)and service(such as pressure vessels),they are inevitably in the presence of hydrogen environment,and the risk of hydrogen-induced damage rupture(hydrogen embrittlement)still exists.However,the emergence of deformation-induced martensite will greatly affect the hydrogen embrittlement sensitivity susceptibility,which makes hydrogen embrittlement still one of the key issues to be paid attention to in this kind of new high-performance materials.Duplex stainless steel in this paper a TRIP as the research object,and connecting with the electrochemical hydrogen-charging,tensile test and micro characterization methods compared the hydrogen effects on the microstructure and the mechanical response characteristics,and emphatically analyzes the annealing temperature,the dependent variable and strain rate on the influence law of the hydrogen embrittlement index(HEI)and the microscopic mechanism.The main results are as follows:In this paper,the effect of hydrogen-charging on the two-phase content and hardness of test steel was studied,and its effect on strength and plasticity index was studied.The fracture characteristics of hydrogen-charged samples were analyzed by SEM,and the relationship between hydrogen diffusion coefficient and mechanical response curve and fracture characteristics was studied.Then,the mechanical response characteristics of the test steel with and without hydrogen at different solution temperatures were studied,and the relationship between the variation trend of hydrogen embrittlement index and fracture characteristics was analyzed.The initiation location and number of hydrogen induced cracks were analyzed by using EBSD and other methods.Then,the morphology and content of martensite in test steel under different pre-strain were studied,and the mechanical response,fracture characteristics and the number of hydrogen-induced crack initiation of test steel were analyzed.Finally,the mechanical response and fracture characteristics of the test steel with and without hydrogen under different strain rates were studied.