Microstructural and thermo-mechanical analysis of quench cracking during the production of bainitic–martensitic railway wheels

• A microstructural and thermo-mechanical FE model to study quench cracking in LCBM railway wheels.
• Extent of martensite phase transformation in lower portion of the rim likely cause of quench cracks.
• Quenching conditions favourable for reducing likelihood of quench cracking are presented.

Quench cracking during the production of newly developed low carbon bainitic–martensitic (LCBM) rail wheels was investigated using a microstructural and thermo-mechanical Finite Element (FE) model. The stresses associated with quench cracking during martensite phase transformation were predicted under various quenching conditions for two different grades of LCBM steels with different kinetics of martensite phase transformation. The FE analyses showed that the likelihood of quench cracking can be reduced by using a low coolant spray intensity since the internal stresses generated during the martensitic phase transformation were found to be below the steel’s flow stress. The internal stresses were predicted to be even lower with a low carbon grade LCBM steel. The microstructural and thermo-mechanical model has been used to determine favourable quenching conditions that have the potential to reduce the propensity of quench cracking during the production of LCBM railway wheels.