Abstract
The effect of friction coefficient on press formability of high strength steel sheet was investigated in this paper. Labo-scale forming test was conducted as press forming test. Galvannealed mild steel sheet and high strength steel sheet were used as base material, and in order to change the friction coefficient three type surfaces were prepared on the same base material. One was as received; galvannealed steel sheet (GA), second was surface modified GA and the third was GA whose surface covered with polystyrene sheet. It was found that both drawability and stretch formability of high strength steel sheet tends to increase with decrease of the friction coefficient. In addition, the effect of friction coefficient on stretch formability was changed depending on punch shoulder radius in stretch formability. The influence of lubrication on drawability and stretch formability and of punch shoulder radius on stretch formability was discussed.
