The temperature equilibrium during hot tensile tests of stainless steels

Real temperature equilibrium within specimens is the basis of reliable resu lts of hot tensile tests. These tests were undertaken with cylindrical spec imens of a ferritic stainless steel AISI 430 and an austenitic stainless st eel AISI 304. The specimens with diameters of 10, 15, 20 and 25 mm were par tially melted. The cooling rates after holding by a maximum temperature var ied between 0.5 and 3.0 K/s. Temperature was measured continuously at the s pecimen center and 3 mm under the specimen surface during the whole test pr ocess. Tests with the smallest specimen diameter and under a slow cooling r ate of 0.5 K/s had even temperature distribution in the radial direction of the specimen so that no duration time is required at any test temperature. Such identical temperature distribution in the cross-section of specimens were changed in different ranges when the specimen diameter was enlarged or the cooling rate was increased. The necessary duration time for the temper ature equilibrium in the radial direction of specimens is explained in deta il in this study that can help the reliability of hot tensile test.