Investigation of the temperature distribution in seamless low-alloy steel pipes during the hot rolling process

In the production of seamless steel pipes, the pipes must have good mechanical material properties so that they meet quality standards. To achieve these properties, the temperature inside the entire pipe should not fall below the limit of normalization immediately after rolling. It is difficult to monitor the quality during the production process by taking measurements, because the measured outer surface temperature does not indicate the temperature inside the pipe. A fast and accurate mathematical model was developed for this purpose. This model can be applied to predict the temperature distribution within the pipe cross section, depending on time required for the production. The section is viewed at points in the production process as the hot tubes are finished by rolling them and cooling them down with air. The predicted time-dependent cooling process must be known to determine the steel pipe microstructure and its mechanical material properties in advance. The results are verified by comparing them with pyrometric and thermographic measurement data as well as with results calculated by using commercially available software. Good agreement is also shown for the calculation of various pipe dimensions.