Yield strength behaviour of carbon steel microsheets after cold forming and after annealing

Microsheets 50 μm thick consisting of DC01 steel were investigated in cold-worked initial state as well as after different heat treatments. Uniaxial tensile tests were carried out and grain size distributions were determined. The best properties with respect to micro cold forming were achieved after annealing for 30 min at 850 °C. These samples show a significant grain coarsening to about 18 μm in diameter. The elongation at maximum load Ag is increased to 16%. Moreover, the thickness of the sheets causes an unusual decrease in yield strength compared to the Hall–Petch relation.