Simulation Study On The Microstructure And Hot Cracking Sensitivity Of Continuous Cast Billets Of S31042 Austenitic Heat-resistant Steel

The continuous casting process of S31042 austenitic heat-resistant steel billet is a complex and dynamic solidification process,which is very easy to form casting problems,such as tissue segregation,composition segregation,shrinkage and shrinkage,fracture,desquaring,and bulging phenomenon.In this paper,the main object of study is S31042 austenitic heat-resistant steel,and the influence of casting temperature and drawing speed on the quality of continuous casting billet is discussed from three aspects: paste zone size,microstructure and thermal crack sensitivity.Firstly,the development history of austenitic heat-resistant steel and the research status of S31042 austenitic heat-resistant steel are outlined,and the mechanism of thermal crack formation is explained,and the research status of thermal crack criterion is analyzed.Secondly,the basic finite element theory of the temperature field is explained,the geometric model of the continuous casting process is established,the mesh is divided by using Pro CAST large casting process simulation software,the initial conditions and boundary conditions related to macroscopic physical field simulation are set,and the steady-state simulation of billet continuous casting process of S31042 austenitic heat-resistant steel is realized.Through the macroscopic physical field simulation of the billet solidification process,the temperature variation of the surface layer of the billet at the end of the crystallizer,the thickness of the billet at the end of the crystallizer and the length of the liquid cavity were obtained,and the solidification heat transfer law at the end of the crystallizer of the continuous casting billet was analyzed.Then,the microstructure of continuous casting process is simulated by using the CAFE module in Pro CAST software.Based on the macro physical field,the simulation conditions and nucleation parameters related to cafe simulation are further calculated and set,the microstructure and grain parameters of billet continuous casting section are obtained,and the effects of different drawing speed and casting temperature on the microstructure of billet continuous casting are analyzed.Finally,the basic functions of the HCS module of Pro CAST software are introduced,and the RDG hot crack criterion used in HCS module is briefly introduced.At the same time,according to the simulation requirements,the three-dimensional geometric model of square billet continuous casting is established,the relevant simulation conditions are set,and the parameters required for HCS simulation are edited as additional input files,so as to obtain the influence law of different drawing speed and casting temperature on the hot crack sensitivity of square billet continuous casting.