Sources of distortion during the production of bar products and beyond∗

When considering the entire production process of a component in respect of distortion, we are able to identify several possible sources of distortion originating in the production of steel bars at the mill. Some of these factors will be presented in this paper and more importantly, possibilities of how to reduce distortion will be discussed. The largest influence on distortion potential in the steel mill arises from the effects of cold working during the straightening process which is essential after the hot rolling and heat treatment steps. The potential problems with cold working have increased in the past years in-line with the increased requirement for higher straightness of bar material produced. The higher the straightness requirement, the higher the level of residual stresses resulting from the straightening process. These residual stresses can lead to distortion during the following production steps. To reduce distortion potentials, new possibilities of controlling the hot rolling process and improved / novel heat treatment possibilities will be presented. In addition to the above mentioned points, the possible sources of distortion potential in the steel casting process will be discussed with reference to the production sequence.