The paper presents a summary of research on the possibility of influencing the state of residual stresses in railway rails by changing the pass design of vertical and horizontal straightener rollers and optimising their distribution on the rail perimeter. The presented results are devoted to the influence of profiled rollers on the level of residual stresses. A wide range of theoretical considerations were carried out based on the use of the finite element method using the commercial Forge software package. In order to verify the results of the theoretical considerations most reliably, a series of “in situ” experiments were conducted in industrial conditions on an existing production line. The tests were carried out on 120 meters long 60E1 railway rails. A significant reduction in the level of residual stresses compared to the standard requirements was achieved.

The article presents the results of the last stage of work on the impact of changes in the roll pass design on the state of residual stresses in railway rails. The discussed stage includes the summary of industrial experiments of rolling 60E1 rails with a length of 120 meters using a modified pass design of roll grooves. The rolling technology has been deeply modified, ranging from the finishing stand, through the pre-finishing stand, to the semi-finishing stand. The rails in this experiment were cooled using standard cooling technology and then straightened using innovative vertical straightener shaped rollers. Residual stresses were tested using the strain gauge method and the hole-drilling strain gauge method by drilling a hole in the rail axis and at a distance of 14 millimetres from its axis. The resulting tensile stresses in the rail foot were reduced to an average level of less than 43% in relation to the requirements of the EN13674-1 standard.

The required rail straightness is achieved by straightening with roller straighteners. The consequence of the straightening operation is the introduction of residual stresses to the straightened rail. An excessive level of residual stresses accumulated in the rail during use in the track may lead to its damage or fracture. ArcelorMittal Poland S.A., in cooperation with Łukasiewicz Research Network – Institute for Ferrous Metallurgy, carried out a research project (POI R.01.02.00-00-0167/16) the aim of which was to reduce residual stresses in railway rails by changing the technological parameters of the straightening process. The results of the presented study relate to rails 60E1 and 60E2. The study includes the measurement, testing, calculations and analyses of the obtained results. The conducted research indicates the possibility of obtaining a low level of residual stress in the rails for a system consisting of a 7-roller vertical straightener and a 9-roller horizontal straightener by changing the roller settings, the shape of the rollers, the shape of the rail foot and its curvature.