Railway wheel steel behaviour upon thermo-mechanical loadings
Licentiate thesis, 2022

Optimised railway maintenance techniques such as rail grinding and milling, or rail repair welding, are vital to more sustainable rail networks. As demands on the railway increases, the need to better understand the material behaviour during local heating events occurring during maintenance is amplified. Other heating events can occur during operation, for instance during severe block braking. This thesis provides insight into thermal damage resulting from these local heating events on railway wheels, which can lead to altered mechanical properties and changed residual stresses.

The material behaviour of the ferritic-pearlitic railway wheel steel ER7T was studied during severe block braking (i.e., slow heating and cooling) at peak temperatures varying between 300 °C and 650 °C. The thermal dilatation was restricted to different degrees between free expansion and full restriction. This study thus explores the combined effect of thermal and mechanical cycling on the mechanical properties and material structure. The experimental results from the thermo-mechanical testing were also used to validate a new constitutive material model for use in FE models to predict severe block braking. 

The second part of the thesis explored the effect of rapid heating and cooling events on the microstructure and residual stress state of railway wheel steel. Localised heating using laser scanning with additive manufacturing equipment was compared to the heating done by scanning with laser welding equipment. This study thus investigated the similarities of different rapid heating (high temperature) processes and the effect of process parameter variations.

The results can be used to provide insight into the material behaviour of railway steels during local heating events. Furthermore, it can support the development of more accurate simulations for both operation and maintenance processes.

residual stress

thermo-mechanical fatigue

railway wheel steel

pearlitic microstructure

severe block braking

repair welding

Virtual Development Lab (VDL), Chalmers Tvärgata 4C, Chalmers University of Technology in Gothenburg
Opponent: Prof. Johan Moverare, Department of Management and Engineering - Engineering Materials, Linköping University

Author

Erika Steyn

Chalmers, Industrial and Materials Science, Engineering Materials

E. Steyn, J. Ahlström. Thermo-mechanical response of near-pearlitic steel heated under restriction of thermal expansion.

E. Voortman Landström, E. Steyn, J. Ahlström, T. Vernersson. Thermomechanical testing and modelling of railway wheel steel.

E. Steyn, J. Ahlström. Simulation of repair welding on pearlitic railway steel using additive manufacturing equipment.

Material characteristics in welding and other local heating events (CHARMEC MU36)

European Commission (EC), 2019-06-10 -- 2024-06-09.

Chalmers Railway Mechanics (CHARMEC) (MU36), 2019-06-10 -- 2024-06-09.

Subject Categories

Other Mechanical Engineering

Manufacturing, Surface and Joining Technology

Other Materials Engineering

Vehicle Engineering

Metallurgy and Metallic Materials

Areas of Advance

Materials Science

Publisher

Chalmers

Virtual Development Lab (VDL), Chalmers Tvärgata 4C, Chalmers University of Technology in Gothenburg

Opponent: Prof. Johan Moverare, Department of Management and Engineering - Engineering Materials, Linköping University

More information

Latest update

10/25/2023