In-line material characterization measurements in high speed rod rolling mills

The ability to provide reliable and timely feedback on the performance of the thermomechanical process in a rolling mill is becoming more important as rolling speeds continue to increase. With rolling speeds now exceeding 120 m/s and production rates exceeding 100 t/h on single strand mills, rapid measurement of the finished product is required to evaluate the process before much unacceptable product is rolled. Conventional means of sample taking, specimen preparation and testing are not only labor-intensive, but also result in relatively slow feedback to the process operators. This paper describes the application of surface volume imaging technology to on-line measurement of pertinent material properties of steel rod. The system examines the microstructural features of the product, such as grain size, crystallographic texture and phase distribution, and correlates those features with mechanical properties such as tensile strength. Furthermore, surface characteristics of the oxide layer can be evaluated and quantified. (author)