Extraction of chordal test specimens from forgings

摘要

A method for making a test specimen includes machining out a chordal core from an annular forging and machining the specimen symmetrical about a chordal axis of the core. A linear cutting tool such as a wire EDM machine is used for the machining which includes at least a partially cylindrical cutting about the chordal axis with the linear cutting tool. A copper or brass tubular EDM electrode may be used. The chordal core may be machined from fat of the forging. The test specimen may have with a gauge section diameter in a range of. 1-.5 inches. The EDM process may include directing jets of machining fluid or dielectric in up and down along a cutting portion of an EDM wire of the EDM machine or performing the EDM process in a tank of machining fluid or dielectric with the annular forging submerged in the fluid or dielectric.