Numerical simulations of welding and other high temperature processes (CHARMEC MU37)

Research Project, 2019 – 2024

Rail and wheel materials are subjected to very high stresses and, in some cases, also to elevated temperatures, and the rolling contact loading results in a multiaxial stress state with a combination of compression and shear. If the temperature in the steel is increased sufficiently and followed by rapid cooling, then austenite and martensite might develop which can be detrimental for the steel properties. Earlier research within CHARMEC has been devoted to models for these phase transformations. However, there is a need to further develop the modelling, e g, regarding the coupling between the phase transformations and the temperature-dependent cyclic mechanical behaviour of the phases in the material. The purpose is to increase the quality in the simulations of residual stresses after the phase transformations and to clarify how the stresses are affected by repeated mechanical contact loading. Project MU37 will be run in co‑operation with a parallel experimental project (MU36) and will use test results to formulate and verify/validate simulation models. The developed models will be used to address applications such as short heating events (e g, braking situations) and welding and grinding of rails. CHARMEC researchers have previously studied thermal processes, both connected to rail welding (MU8, EU15 WRIST), laser cladding (MU7, EU7 INFRASTAR, MU15) and thermal damage induced by contact friction heating (MU2, 3, 23, 29, 30, 32). Project MU37 will build on previous works, and the outcome will lead to accurate and predictive methods supporting technology development and decreasing LCC.

This is a doctoral project. Mr Björn Andersson is the doctoral student and Professor Magnus Ekh the project leader and supervisor. Professors Johan Ahlström and Lennart Josefson are assistant supervisors.