Study On Dynamic Model Of Martensitic Transformation Of TRIP Duplex Stainless Steel Under Cyclic Loading

The economical duplex stainless steel has excellent mechanics,light weight,long service life and other advantages,and has a good prospect in the application of rail transit and new energy car body.The use of Mn-N dielement instead of expensive metal N i in stainless steel results in metastable austenite phase in economical duplex stainless steel,and strain-induced phase transformation effect occurs during plastic deformation.Since TRIP effect can enhance the plasticity and strength of materials,it is important to clarify the martensitic transformation of TRIP duplex stainless steel for further development and application of high performance TRIP duplex stainless steel.TRIP duplex stainless steel is often subjected to repeated loads in practica l applications.Furthermore,due to the difference in the properties of austenitic and ferrite phases in TRIP duplex stainless steel,there is a significant interphase strain partitioning and deformation-induced phase transformation interaction during cyclic plastic deformation.However,at present,for TRIP duplex stainless steel with high performance and economy,the relationship between martensitic phase transformation and phase strain distribution under cyclic loading is not clear,and there is a lack o f martensitic dynamic model reflecting the uneven characteristics of phase deformation.In this paper,comprehensive theoretical analysis and experimental research method,the TRIP duplex stainless steel under the condition of cyclic loading of martensitic phase transformation rule is analyzed,according to the shear zone nucleation theory,based on the existing model is established to describe cyclic loading conditions dismount austenite phase shift amount and the total strain amplitude and the cumulative plastic strain relationship model,The dynamic model of cyclic "apparent" martensitic transformation;The relationship between the deformation law and the total deformation was studied by EBSD microstructure observation test,and the strain partition model was established.Combined with the cyclic "apparent" dynamic model and strain partition model,a cyclic "true" martensitic transformation dynamic model was established to reflect the uneven deformation characteristics of the components.The effect of deformation inhomogeneity on martensitic transformation was analyzed.