Test body ASTM D250

Test body for determining the magnetic field direction and testing the sensitivity of the entire magnetic particle system.

Properties and area of application

The D 250 is an octagonal, approx. 3 mm thick test body consisting of 8 individual segments.
The gaps between the soft iron segments, which are filled with brazing alloy, have a maximum width of 0.79 mm (1/32 inch).
One side of the test body is plated with copper.

If the unplated side of the D 250 is placed on a magnetized test object, some of the magnetic lines of force flow through the soft iron segments. If the magnetization is sufficient, stray fluxes occur at the seams.
After rinsing with magnetic powder suspension, one or more linear indications are formed on the copper cladding at a 45° angle to each other.

To determine the direction of the magnetic field, the test specimen is slowly rotated around its vertical axis until the indication of one of the lines is most pronounced. The determined magnetic field direction then runs perpendicular to it.

 Technical data