When conducting acceptance tensile testing of ductile iron(as specified by ASTM A746), it is necessary to test machined specimens. This specimen is known as a shouldered-end specimen. Sometimes referred to as a "dumbbell", "dogbone" or "button-end specimen", this round specimen type has shouldered ends that are used for gripping the specimen during testing.
Modern ASTM A746 tests need to be run at specific stress rates under servo control and require an extensometer for accurate calculation of 0.2% Offset Yield and Ultimate Tensile Strength.
Today’s customers require automated controls and precise measurements to ensure that their ductile iron pipe product is viable before it gets buried underground. These contemporary needs make older testing techniques, such as manual pacing or drop-of-beam observations, unsuitable.
We have provided systems for tensile testing standard 0.505 in diameter shouldered end specimens, 0.750 in diameter specimens and smaller sized specimens called out in ASTM A746. Since the maximum load requirement for these sizes is approximately 30,000 lbf, we recommend using an Industrial Series 300LX load frame with split insert tensile grips and holders. These tensile grips are designed specifically for testing ductile iron specimens and adapt to the test frame with our Universal Spherical Tension Adapters (USTA). The USTA adapters ;provide necessary specimen alignment.
The single test space and dual acting actuator of the 300LX make it easy for operators to install the specimens. The split sleeve shouldered end specimen holders allow for quick changing of test specimens. They also contain the ends of the broken specimen during failure providing an extra level of operator safety. The USTA assemblies enable the specimen to self-align during loading, easily meeting the alignment requirements of ASTM E8.
Partner™ or Bluehill ® Materials Testing Software packages provide the necessary control parameters and calculation algorithms to satisfy the ASTM E8 and ASTM A746 test standards. In addtion, the software's offer simple test setup and efficient testing operation.