Application of the Metallurgical Model to Hot Strip Rolling of Plain Carbon Steels

摘要

A computer model based on physical metallurgy was developed for plain carbon steels, and was applied to practice for prediction of mechanical properties and control of the hot strip processing conditions. Computer modelling was carried out to describe the microstructural evolution during hot rolling and cooling and the interrelationships existing between microstructure and mechanical properties. The mathematical model consists of three sub- models: austenite conditioning model, transformation model and mechanical property model. The austenite conditioning model deals with recovery, recrystallization and grain growth which occur during hot rolling. The allotropic phase transformations from austenite to ferrite, pearlite and bainite are described by the transformation model. The final mechanical properties are determined from the structure-property relationships established in the mechanical property model. Applying the model to practical hot strip rolling, the computer systems for on-line prediction and alloy/process design were developed. The on-line prediction system enabled the prediction of microstructure and mechanical property variation along the length of a hot coil whenever the coil emerged from the coiler. It was found that the predicted values of tensile strength of hot strips processed under various rolling conditions were in reasonable agreement with the measured ones. The alloy/process design system enabled the modification of the preset hot rolling parameters, i.e. coiling temperature, so that the desired mechanical properties could be obtained. It was found that the number of steels could significantly be reduced and the processing conditions could be more precisely controlled when the design system was utilized.