Development of a Pneumatic Bulge Test for High Temperatures and Controlled Strain Rates

Abstract

Due to new material concepts (e.g. boron-manganese steels), hot stamping of sheet metal parts has emerged in order to produce high strength components. Thereby, the design of hot stamping processes by means of finite element simulations requires information about the thermo-mechanical material behaviour up to high strain levels at various temperatures as simulation input. It is known that hot tensile tests are only evaluable until low strain levels. Therefore, a hot gas bulge test for temperatures in the range of 600 °C to 900 °C and strain rates up to 1/s is being developed. In order to design such a hot gas bulge test, the requirements (e.g. forming pressure) are estimated by finite element simulations. The result is a test bench, which already enables a pneumatic forming of specimens at room temperature and pressures up to 200 bar without any unexpected side effects.

Hot tensile and expansion tests of Ductibor®1000 steel

“…Li et al [9] investigated the formability of the AZ31 magnesium alloy using a bulge test device and pulse current to heat a rectangular sheet at 400 °C. In their work, Braun et al [10,11,12] developed a hot gas bulge test device with resistance heating of rectangular sheets to characterize quenchable steels up to 900 °C. In this paper, a bulge test device using resistance heating to characterize metal sheets up to 900 °C is presented.…”