The Competition Segregation Behavior Of Boron And Tin In Steel And Its Effect On Microstructure And Properties

In this paper,Gleeble thermal-mechanical simulation tester and electron backscatter diffraction system(EBSD),in-situ Auger spectrometer(AES),optical microscope(OM)and Brinell hardness tester,etc.are used to solve the common problem that the residual element Sn tends to segregate toward the grain boundary during the thermoplastic deformation process such as continuous casting,reduce the intergranular cohesion,and deteriorate the thermoplasticity of the slab,mainly studied the competitive segregation behavior of boron and tin in steel during thermoplastic deformation The impact of organization and performance has reached the following main conclusions:In this paper,the precipitation of BN in the steel can be effectively controlled,by controlling the N content in the steel and adding a small amount of Ti,so that the boron in the steel exists in the form of a solid solution state,which is its role in the subsequent thermal history.Segregation and suppression of grain boundary segregation of other elements provide the possibility.In addition,as the B content increases,the grain size of the experimental steel after annealing increases first and then decreases,and the Brinell hardness decreases first and then increases.When the B content is 34 ppm,the grain size of the experimental steel after annealing is the largest,the average size is as high as 216?m,and the hardness is also the lowest,59.8HB.When the B content exceeds 60 ppm,the grain size of the experimental steel gradually decreases after annealing,and the hardness gradually increases.In addition,with the increase of the boron content in the steel,the initial transformation temperature of the experimental steel gradually decreased;when the boron content was 34-91 ppm,the transformation temperature decreased by 3-5.8?.With the decrease of the deformation temperature,the increase of the strain rate and the increase of the strain variable,the content of the low ?CSL grain boundary in the experimental steel decreases,and the amount of Sn grain boundary segregation gradually increases.In addition,during the thermoplastic deformation process,boron undergoes significant grain boundary segregation,which can preferentially occupy the grain boundary segregation position and suppress the grain boundary segregation of Sn in steel.And the amount of boron grain boundary segregation increases as the deformation temperature decreases,the strain rate increases,and the amount of strain increases.As the boron content increases,the content of low ?CSL grain boundaries in the steel gradually increases.During the thermoplastic deformation process,the grain boundary segregation of Sn in Sn5B0 steel is the most serious.The atomic percentage of Sn at the grain boundary is 0.63%.The addition of boron can suppress the grain boundary segregation of Sn in the steel,as the content of boron increases The amount of Sn grain boundary segregation gradually decreased.Under this test condition,when the amount of boron added was 91 ppm,the atomic percentage of Sn in the grain boundary decreased to 0.2%,and the Sn content in the grain boundary decreased by 68.3%.In addition,with the increase of boron content,the amount of segregation of grain boundary B during the thermoplastic deformation also gradually increased.In addition,the {111}<110> and {110}<110> texture components are the strongest in the experimental steel without boron,while the {001}<110> texture components are the weakest.With the increase of boron content,the texture strength of{111}<110> and {110}<110> decreased,while the texture strength of {001}<110> increased.