Simulation of Symmetric and Asymmetric Shape Rolling Processes

Abstract

Steel is still a dominant structural material in use today and will be in the foreseeable future. It is estimated that the rolling process is used in 80-90% of the steel production worldwide. However, there are currently no off-line tools commercially available to predict a priori the microstructure and hence, the mechanical and geometric properties, of a rolled product after the steel has been subjected to the series of operations necessary for obtaining the desired shape. Consequently, attempts to correlate the rolling characteristics with mechanical properties and microstructure in the finished product have been predominantly empirical in nature. These empirical models may at best be valid under conditions that were used to generate the data, i.e. specific mill conditions and/or type of steel, but do not provide a detailed description of parameters throughout the product. Rod and bar customers today are demanding tighter specifications for tolerances on geometric, mechanical and microstructure properties to satisfy the requirements of the products they manufacture. This presents a problem for many rolling mill operators, who are accustomed to meeting stringent requirements on geometric and mechanical properties but not microstructural parameters. In order to determine precise mechanical equipment and processing necessary for optimizing the microstructure, more sophisticated computer models of deformation and microstructure evolution are needed. The coupling of the rolling process simulation with both deformation and microstructure evolution is a capability that is missing in the steel industry - as cited by a Steel Roundtable held in 1998 by the American Iron and Steel Institute (AISI). The goal of this project is to develop an off-line finite element model of hot rolling process to simulate mechanical deformation of rod and bar rolling that can be used by mill engineers in the steel industry and compare the results with experimental data and various empirical models.