Revisiting flow stress modelling for simulating chip formation of carbon and low alloy steels

In previous papers the present author has successfully predicted chip formation in machining carbon steels with a model that supposes all carbon steels to have the same flow stress thermal softening and a temperature independent strain rate hardening but to be characterized by individual strain hardening behaviours. It has been necessary to suppose thermal softening to be shifted to higher temperatures than observed experimentally. It is now found alternatively that the thermal softening shift is not required if it is supposed that the strain rate hardening increases slightly in proportion to temperature at temperatures greater than 600°C. The new model results are illustrated and compared to experiment for the low alloy steel BS970:708M40. The relation between flow stress and friction modelling is also discussed.