ASTM B406-96(R2021) pdf free download

ASTM B406-96(R2021) pdf free download.Standard Test Method for Transverse Rupture Strength of Cemented Carbides
1. Scope
1.1 This test method 2 covers the determination of the transverse rupture strength of cemented carbides. 1.2 The values stated in inch-pound units are to be regarded as the standard. The SI values in parentheses are provided for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Significance and Use
3.1 This test method is used as a means of determining the quality of cemented carbide grade powders by measuring their sintered strength. It is performed on test specimens prepared to specified shape, dimensions, and surface finish; test specimens may be prepared from finished parts ifsize permits. There is no known standard material for this test method. The transverse rupture strength of cemented carbides is not a design value. 3.1.1 Most commercial cemented carbides have mechanical behavior that is best classified as brittle (negligible ductility). Fracture strengths are dependent on internal or surface flaws. Examples of incoherent internal flaws are macropores, Type B porosity (see Test Method B276), and inclusions of foreign particles. Such flaws are randomly distributed spatially and in size within the sintered 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 be used. In either case, the apparatus shall have the following parts: 4.1.1 Two ground-cemented-carbide cylinders 0.250 6 0.001 in. (6.35 6 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 6 0.005 in. (14.3 6 0.1 mm). 4.1.2 Amovable 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 6 0.05-in. (10 6 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 ball or cylinder to contact a specimen placed on the two lower cylinders at the midpoint of the span between them.4.1.3 The apparatus shall be so constructed that the appli- cation of a sufficient load to the movable member to effect breaking ofa specimen will not cause appreciable deflection of the line of movement of the movable member and the plane established by the two fixed cylinders. The apparatus shall be capable of applying sufficient load to break the specimen. The apparatus shall be capable of registering the load required (within 61 % of the load) to break the specimen. The cemented-tungsten-carbide ball and cylinders shall not show permanent deformation after use.