Validated material data sets are necessary for reliable simulation results in forming technology. This also applies to the application of flow curves. The flow curves database of MatILDa® contains numerous flow curve data sets based on experimental investigations. Hot flow curves and cold flow curves provide a qualified basis for material calculations as a function of forming temperature, true strain and strain rate in analytical (approximated) or tabular form.
Other important parameters influencing the flow stress, such as the microstructure of the material, the heat treatment condition of the material (e.g. mill-hard, normalized or soft-annealed) and the stress condition in the selected forming process (tension, compression or torsion) can be taken from the respective flow curve model and selected according to the conditions in the real forming process.
Validity ranges of flow stress models
It is also crucial that corresponding validity ranges for flow stress models are specified, which in the best case fits the real process windows. The significant influence can be illustrated by simulation results: within the FEM simulation of a common upsetting test, flow curves from the MatILDa® flow curves database were used, which have different validity ranges. This illustrates that there is a significant difference on the resulting force in the FEM results whether a flow curve from an upsetting or a torsion test was used. Similarly, there is a clear difference in the case of different heat treatment conditions. It can be concluded that it is very important to select the flow curve data according to the conditions in the process – and not to use flow curves with undefined ranges of validity.
FEM results for an upsetting test using flow curves from the MatILDa® flow curves database with different validity ranges
Type of experimental setting
(100Cr6 / 1.3505, T = 1000 °C)
Heat treatment condition
(41Cr4 / 1.7035, T = 500 °C)
The validity range is precisely defined in the flow curve database in MatILDa® in the flow curve parameters as Measured range and Function usable. In the comment, notes on the experimental settings are listed.
Functionalities of the flow curves database
The flow curve database in MatILDa® contains hot flow curves and cold flow curves with different approaches according to Hensel / Spittel or including the yield point at elevated temperature for metallic materials. The user has the possibility to use the stored flow curves for a material or to perform an approximation as well as to use own flow curves. The parameterized flow curve description can be carried out according to various approaches, including Hensel / Spittel or the GMT approach with or without consideration of the yield point at elevated temperature.
The flow curve database is available for various alloys of steel, non-ferrous metals (e.g. aluminum, copper, magnesium) as well as special materials (e.g. titanium, nickel, cobalt).
Please also read our publications about flow curves: