Crystal Plasticity Simulation Study On The Effect Of Microstructure Of P92 Steel On Mechanical Behavior

As a representative of ultra-supercritical thermal power steel,P92 heat-resistant steel has good high-temperature creep mechanical properties and corrosion resistance.However,the evolution of the second phase particles,dislocation density and martensitic laths during actual service will affect the high-temperature mechanical properties of P92 steel and reduce the service life.Therefore,evaluating the influence of the microstructure on the mechanical properties of P92 steel has practical engineering significance.Studies have shown that the evolution of multiple microstructures of P92 steel occurs at the same time when it is in service.It is difficult to distinguish the effects of individual microstructure characteristics on specific mechanical properties through experimental methods.At the same time,there is a lack of research on the microplastic deformation mechanism of P92 steel.For this reason,this paper establishes the crystal plasticity finite element model of the physical mechanism of P92 steel to explore the microscopic plastic deformation mechanism of P92 steel,and the influence of the second phase particles M₂₃C₆and lath structure on the plastic deformation of P92 steel.(1)The tensile deformation behavior of P92 steel is simulated and analyzed by the crystal plasticity finite element model.Explore the influence of slip system and typical texture on the tensile strength of P92 steel.The results show that P92heat-resistant steel exhibits uneven plastic deformation.There are dislocation plugging and stress and strain concentration phenomena at the grain boundary,which are easy to cause crack initiation and damage and cracking at the grain boundary.Consistent with related experimental studies,among the three main slip systems,the activation of the P92 steel slip system is mainly concentrated on the{110}<111>slip system.The texture has a significant effect on the plastic deformation of P92 steel,which conforms to Schmidt's law.Under the action of[001](11 0)texture,the smallest Schmidt factor is obtained,and it has a higher strain hardening index and stronger resistance to plastic deformation.(2)In order to explore the influence of the precipitation amount and microstructure characteristics of M₂₃C₆on the high temperature plastic deformation of P92 steel.A two-dimensional crystal plasticity model containing M₂₃C₆was established,and the tensile behavior of P92 steel at 600?was simulated and analyzed.The results show that with the increase of the amount of M₂₃C₆precipitated,the model has an obvious strain gradient,which intensifies the inhomogeneity of local plastic deformation.Strain concentration and high dislocation density often appear at the junction of M₂₃C₆and the matrix,and at the same time form an angle of about 45°with the loading direction.Among them,the smooth rod-shaped and spherical M₂₃C₆are beneficial to alleviate the strain concentration.Among the three orientation relationships between M₂₃C₆and the matrix,the Pitsch orientation relationship is more conducive to reducing local strain concentration and alleviating dislocation packing.(3)In order to explore the characteristics of slat orientation structure and the influence of coarsening behavior on creep behavior,slat models of different sizes were established.The creep behavior of P92 steel under high stress at 650?was simulated,and the influence of the relationship between grain boundary angle and crystal orientation on creep properties was deeply explored.The results show that the roughening of the slats reduces the hardening strength of P92 steel,promotes the activation of the slip system,and causes the creep deformation rate to accelerate.The distribution of grain boundary angles in the lath structure is mainly concentrated in the range of 2°?6°and 50°?60°.Small-angle grain boundaries are conducive to plastic deformation,and large-angle grain boundaries hinder plastic deformation.The transformed martensite lath and the austenite parent phase grains are connected by a special orientation relationship.In the typical orientation relationship,the G-T orientation helps to maintain the creep strength of the lath structure.