Thermal Simulation Study Of Controlled Rolling And Controlled Cooling Process For G20CrNi2MoA Bearing Steel

With the continuous innovation of the process of industrialization,in order to meet the needs of the development of the age of science and technology,bearing as the core component of the mechanical equipment has a new requirement for its comprehensive performance.Trace to its source,by optimizing the processing technology to improve the comprehensive performance of bearing steel,there is a wider market space and more far-reaching significance.As a new and advanced processing technology,the controlled rolling and controlled cooling process has been given a very important historical mission.In this paper,taking G20CrNi2MoA high quality bearing steel as the research object.The deformation resistance of G20CrNi2MoA bearing steel,the law of continuous cooling continuous phase transformation and the specific influence of the deformation parameters on the structure and properties of the bearing steel are systematically studied by the thermal simulation method.The database of stress strain and thermal expansion of the steel is perfected.Finally,the best controlled rolling and controlled cooling process suitable for this kind of steel is determined,which provides reference for actual production.In the process of thermal simulation compression test,through the linear regression analysis of stress and strain test data,the deformation resistance model of G20CrNi2MoA bearing steel is established:(?)and the theoretical data calculated by the model are in good agreement with the measured stress data.For G20CrNi2MoA steel,during continuous cooling transformation.The transition temperature of pearlite occurs at a lower cooling rate.The transition temperature is between 600?-700?.With the increase of cooling speed.The bainite transformation is carried out in the range of 400 ??580?.When the cooling rate is greater than 10?/s,martensite transformation occurs only and the starting temperature of martensite transformation is 409 C.At the same time,in the cooling process,The mechanical properties increase with the increase of cooling speed.Through the study of the influence of the deformation parameters on the structure and properties,the optimal process parameters that can make austenitizing more fully,more uniform and better performance are determined.Based on the results of this study.The deformation temperature is 900? and the deformation degree is 30%.After finishing rolling,a higher cooling rate is used to cool the bainite phase transition temperature,in order to avoid the precipitation of ferrite,and then cooling to room temperature controlled rolling and controlled cooling at a cooling rate of 2?/s.The microstructure of the bainite is smaller than that of the original sample,and its comprehensive mechanical properties are better than those of the original sample.This result provides a theoretical basis for the application of controlled rolling and controlled cooling technology in the actual production of G20CrNi2MoA bearing steel.