Simulation Study On The Evolution Behavior Of Alumina Inclusions In Rolled Thick Plates Of Offshore Steel

Heavy plate of offshore steel is widely used in the construction of ships and offshore platforms,due to the particularity of the application,the performance requirements for steel plate are very high,the current smelting technology can not completely remove the non-metallic inclusions in the steel,most of the smelting process to add aluminum alloy as a deoxidizer,so the production of Al₂O₃ inclusions is inevitable,its existence will seriously affect the performance of the steel plate.For offshore steel plates,excessive thickness of the steel plate will lead to uneven thickness deformation,resulting in the inclusion cannot be broken,so it is of great significance to explore the deformation behavior of inclusions in offshore steel plates under different rolling processes.This paper mainly studies the evolution behavior of inclusions during the rolling process of offshore steel plate,establishes a finite element model of thick plate rolling,and analyzes the influence of different heat transfer coefficients on the distribution of temperature field in the thickness direction of steel plate during the cooling process before rolling.The influence of different process parameters（depression rate,heat transfer coefficient）on the distribution law of the effect variation of the thickness direction of the steel plate was analyzed.Based on Python programming,the Cohesive unit with 0thickness is embedded in batches between the inclusion-matrix elements,the Al₂O₃inclusion cohesion model is established,and the rolling thick plate model containing inclusions is established through finite element sub-model technology,and the influence of different rolling processes,different inclusion shapes,inclusion sizes and inclusion positions on the inclusion crushing behavior is simulated and analyzed,and the double inclusion model under different relative position and distance conditions is simulated and analyzed.The crystal plastic finite element method is used to simulate the influence of the sub-inclusion on the matrix,and then the damage principle of the matrix near the inclusion is analyzed from the meso-scale.The thermal compression experiment was used to simulate the inclusion steel,and the morphology and composition of inclusions under different influencing factors were analyzed by metallographic microscopy,scanning electron microscopy and EDS and other material characterization methods,and through the comparison and analysis with the previous finite element simulation results,the evolution law of inclusions in rolled thick plate under different influencing factors is obtained:With the increase of heat transfer coefficient and rolling pressure rate,the deformation of the steel plate thickness plate is deeper and more uniform,and the degree of inclusion fragmentation at the core position is greater.Cube inclusions with geometric corners are easier to break than sphere inclusions,and the degree of fragmentation is greater;The larger the inclusion size,the greater the degree of fragmentation of the inclusion;When the two inclusions are close to each other,the inclusions with relative positions in front and above are more broken,and more defects are easily formed.There is obvious interference between the stress field around the two sub-inclusions generated after crushing,and defects are easy to occur at this location,and grain boundaries can hinder the generation or expansion of defects;The results of thermal simulation experiments are consistent with the results of finite element simulations.