Calculation Of Thermal Stress And Thermal Fatigue Life Of Zirconia Coating On Pulling Straightening Roller Of Continuous Casting Machine

As an important part of continuous casting machine,the working environment is very bad.Under the periodic action of heat transfer and cooling water of slab at 1000 ?,cracks and surface layer fall off easily.The surface quality of the drawing straightening roll of the continuous casting machine is directly related to the quality of the billet and the production efficiency and economic benefit of the enterprise,so it is imperative to improve the service life of the drawing straightening roll of the continuous casting machine.Zirconia coating with low thermal conductivity,high temperature oxidation,high temperature stability and other characteristics,not only can play a role in oxidation,but also improve the caster straightening roller thermal shock resistance.This project will use plasma spray technology to prepare zirconia coatings,and design related experiments to study the performance of the coatings,aiming to find ways to improve the service life of straightening rollers.Firstly,zirconia coating were prepared on H13 by plasma spray technique.Thermal shock tests were performed on the samples.The microstructure of zirconia coatings before and after thermal shock was observed by SEM and EDS appearance.The results show that the failure location of the zirconia coating is between the ceramic layer and the tie layer.Secondly,the experimental device of the straightening roller was designed and the heat insulation experiment of the straightening roller was carried out.The temperature change curve of zirconia coated roll surface was recorded and plotted.The influence of the coating and the thickness of the coating on the roll surface temperature was summarized,and the optimum coating thickness was selected.Finally,taking the straightening roller as the research object,the boundary conditions of the straightening roller temperature field are expatiated.The model is simplified and the heat transfer coefficient of the straightening roller is derived by the basic laws of thermodynamics.The finite element software ABAQUS was used to simulate and analyze the straightening rollers of the conventional and zirconia coating respectively.Thetemperature and stress of the two straightening rollers were compared.Surface temperature and the feasibility of reducing thermal stress.According to the finite element simulation results of ABAQUS,the fatigue life of the straightening roller in the uncoated and coated condition was estimated by fatigue analysis software FE-SAFE.