Research On Shrinkage And Porosity Of Centrifugal Composite Casting Roll Body

China is the leader in global steel production and consumption,and its crude steel output has remained the first in the world for more than 20 years.The roll is the key equipment on the steel rolling mill,and is also its main consumption part.The consumption cost of roll accounts for about 5%～15% of the total cost,so it plays an important role in the whole production process.With the continuous development of the iron and steel industry,the size,operating efficiency,structural complexity and automation of production equipment such as rolling mills are increasing,so are the requirements for roll performance and quality.For example,for the high chromium cast iron roll used in the front section of finish rolling,it is required that the bottom wave attenuation shall not occur at the roll body position during ultrasonic testing(that is,the echo attenuation amplitude at any position shall not exceed 10% of the full screen amplitude).The main reason for the attenuation of the bottom wave of the roller body is the shrinkage porosity defect,which is also a prominent problem affecting the yield of high chromium cast iron rollers and causing waste of factory resources.In this paper,numerical simulation technology is used to establish a numerical model of roll centrifugal composite casting process,and then a systematic study is carried out on the factors affecting the shrinkage and shrinkage holes of the roll body,and the methods and means of numerical simulation experiments,physical and chemical inspection and analysis,and actual process data collection are used to clarify the laws affecting the shrinkage and shrinkage holes of the roll body,so as to guide the design of the roll centrifugal composite casting process.The main contents of this study include:(1)By using three-dimensional modeling software and numerical simulation software,the 3D model and finite element model of roll casting are established to study the flow,solidification process changes and shrinkage porosity defects in the process of centrifugal composite casting of roll.(2)Analysis of the causes and influencing factors of shrinkage defects in roll casting,using the established model to analyze the influencing factors of existing casting process on shrinkage defects,and then find out the methods to reduce or eliminate shrinkage defects.(3)The process is tracked at the production site,the temperature curve is determined,and the temperature of the cold outer surface of the high chromium cast iron roll is compared with the simulation results in the actual production process to verify the correctness of the model establishment and numerical simulation.