The development of a new deformation regime for microstructure refinement in solid railway axles by hot deformation optimization

Abstract

Goal. During the production of railway axles, the main target is to obtain a uniform metal structure with a grain size not larger than number 5 across the entire section of the produced axle. Moreover, in accordance with the demands of railway axle consumers, the differences in grain size numbers should not exceed 2. However, due to multi-stage processing and repeated heating of axle material, the fulfillment of aforesaid requirements is very difficult and the differences in grain size numbers are usually found as 4. Therefore, it is necessary to develop a special deformation regime for controlling the sizes and the uniformities of metal grains in the finished product. Methods. We employed experimental and theoretical investigations to reveal the microstructure refinement in the deformation zone of the produced railway axle. The experimental investigation was carried out under the production conditions, whereas the theoretical investigation was performed based on the theory of plasticity and finite element method. Results. Furthermore, the regularities of process parameters in the deformation zone were revealed; hence, a new deformation regime was developed, and consequently, the quality of the finished railway axle was improved. Scientific novelty. Rolling of solid railway axle required special de-formation regimes that differed from the deformation regimes for rolling of other types of products. Deformations in vertical and edging directions with edging reduction were less penetrative to the central zone of the billet as compared to surface layers, thus resulting in an increase in energy consumption and equipment load of the rolling mill. Rolling with edging reduction caused a worse de-formation at the central zone of the billet in the box caliber.Rolling without edging reduction caused large deformations in central layers of the billet and led to a significant improvement in the metal structure of the axle.