Temperature and flow stress during the hot extrusion of steel

AbstractMild steel and type 316 stainless-steel billets have been extruded to bar through flat dies using glass lubrication, reheating temperatures of 1070°, 1170°, and 1280°C, and ram speeds of 25–240 mm/s. The low effective coefficient of friction (0·002–0·011) under these conditions leads to extrusion without formation of a dead-metal zone, and hence to a low redundant work/actor. Temperature losses to the atmosphere and to the container after upset of the billet have been measured and used to determine the mean temperature as afunction of ram travel. From the effect of mean temperature on the flow stress determined from torsion tests, extrusion pressure curves have been calculated to within ±5% of the observed curves.