Bulk Materials Testing
The focus of the material testing at the IBF is the destructive testing under tension, compression, bending and torsion. Besides the execution of standardized and non-standardized tests, the IBF also develops new testing methods and devices e.g. hot gas bulge test.
Available Tests at IBF
- Tensile test with round specimens
- Compression test
- Torsion test
Tensile Test on Round SpecimenCopyright: © IBF
To determine flow curves under tensile load and material properties, the Institute of Metal Forming offers tensile tests. In this process, the specimen is drawn to fracture under quasi-static forming conditions on a universal testing machine. During the forming process, the force is measured by means of a load cell and the change in length of the specimen is measured without contact by means of a video extensometer. From this, both the true stress-strain diagram and the engineering stress-strain diagram can subsequently be calculated. The technical stress-strain diagram can be used to determine typical parameters such as yield strength, tensile strength and uniform elongation.
Upsetting TestCopyright: © IBF
For the determination of dynamic flow curve fields for the numerical simulation of bulk forming processes, the isothermal cylindrical upsetting test is carried out at the Institute of Metal Forming. In this test, a cylindrical solid specimen is upset to a defined final height at dynamic strain rates and variable temperatures. The use of lubricants such as Teflon, boron nitride, graphite or molten glass ensures almost friction-free forming. Continuously measured machine displacement and upsetting force enable the calculation of the friction-free and isothermal flow curve. The temperature compensation offered at the IBF additionally compensates for dissipation-related influences on the flow curve.
Torsion TestCopyright: © IBF
Compared to other methods of flow curve determination, such as tensile or compression tests, the torsion test enables the determination of flow curves up to higher strains. Torsion tests are carried out at the Institute of Metal Forming on the STD 812 torsion plastometer. The specimens used are round bars with a diameter of 16 mm, which have a conical taper in the forming zone. The test temperature can be selected in a range from room temperature to 1500 °C. Strains up to 32 can be achieved on the equipment. The strain rate can be controlled within the interval 0.001 to 9 s-1. Alternatively, the specimen’s deformation can controlled by displacement or torque.