ASTM B406-96 (R2021) pdf download.Standard Test Method for Transverse Rupture Strength of Cemented Carbides.
1.1 This test method2 covers the determination of the transverse rupture strength of cemented carbides.
1.2 The values stated in inch-pound units are to he regarded as the standard. The SI values in parentheses are provided for information only.
3.1.1 Most commercial cemented carhides have mechanical behavior that is best classified as brittle (negligible ductility). Fracture strengths arc dependent on internal or surface flaws. Examples of incoherent internal flaws arc macropores, Type B porosity (see Test Method B276). and inclusions of foreign particles. Such flaws are randomly distributed spatially and in size within the sintercd material. This imparts a statistical nature to any transverse rupture strength measurement.
3.1.2 The stress distribution in a beam in three-point loading is non-uniform. It increases linearly along the span to a maximum at the center, and varies linearly through any section from compression on the top to tension on the bottom. The maximum tensile stress therefore occurs at center span in the bottom most fIbers of the sample. and is defined as the transverse rupture strength at failure. Failure is initiated at a random flaw site, which is most probably not coincident with the maximum stress. This imparts an additional statistical nature to transverse rupture strength measurements.
4. Apparatus
4.1 Either a specially adapted machine for applying the load or a special fixture suitable for use with a conventional load-applying machine may he used. In either case, the apparatus shall have the following parts:
4.1.1 Two ground-cemented-carbide cylinders 0.250 ± 0.001 in. (6.35 ± 0.02 mm) in diameter, at least 0.500 in. (13 mm) in length with the long axes parallel, and center to center spacing of 0.563 ± 0.005 in. (14.3 ± 0.1 mm).
4.1.2 A movable member (free to move substantially only in a line perpendicular to the plane established by the axes of the two cylinders) containing a 0.4 ± 0.05-in. (10 ± 1.3-mm) cemented-tungsten-carbide ball or a ground-cemented-carbide cylinder of the same dimensions as, and with axis parallel to, those of the two previously mentioned cylinders (see 4.1.1). This ball or cylinder shall be so positioned that movements of the member will cause the hail or cylinder to contact a specimen placed on the two lower cylinders at the midpoint of the span between them.ASTM B406 pdf download.