An industrial application case to predict galling in hot stamping processes

Abstract

Severe tool wear is an unwanted phenomenon which occurs widely during hot stamping processes due to extreme process conditions like high temperatures and the absence of lubricant. Galling is a wear mechanism in the form of adhesive wear in which some material from the sheet transfers to the tooling. In a longer term, the build-up of material on the tool can damage the sheet in the form of scratches and can negatively affect the heat transfer between sheet and tool. Therefore, it is important to develop advanced models to predict and control tool wear and galling during hot stamping processes. More recently an advanced friction model for hot stamping processes has been introduced to accurately describe frictional behavior of 22MnB5-AlSi. This study aims to further extend the advanced friction model of 22MnB5-AlSi into a galling prediction tool by first evaluating possible galling initiation models and next assessing growth models. These models are calibrated using experimental data from hot strip draw tests performed at Tata Steel. This results in a multi-dimensional galling model as a function of temperature, pressure, strain and also on the relative sliding distance in contact between the tool and the sheet. Finally, the predicted galling distribution on the tooling surfaces for two industrial parts from Volvo Cars are verified. The galling locations are accurately found on the parts by the applied galling model.