Fracture toughness test method
AssigneeReed Tool Company
InventorLynn M. Barker
Life of this patent
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Abstract
An improved method for testing fracture toughness of tungsten carbide, and more particularly sintered tungsten carbide, consists of preparing a specimen from a short rod of sample material by cutting thin longitudinal slots forming a V within the slotted portion of the sample. An initial crack is started at the tip of the V formed by the slots. After the initial crack is started, the specimen is loaded with a force perpendicular to the slot plane and the peak force required in advancing the crack is recorded. The peak force is linearly related to the critical stress intensity factor (fracture toughness) of the specimen material.
Claims12
A method of measuring the fracture toughness of hard brittle materials comprising
- forming a short rod-shaped test specimen,
- cutting slots in said specimen in a single plane intersecting to form a single slot having an internal V shape,
- applying an opening force at the open end of said single slot to form an initial short crack at the apex of said V,
- applying slowly increasing forces to the slotted end of said specimen perpendicular to said slot in opposite directions tending to open said slot and propagate said crack, and
- measuring the peak force applied in propagating said crack prior to breaking said specimen,
- said peak force being linearly related to the fracture toughness of the specimen.
Dependencies are inferred from the claim text.