Transverse Rupture Strength Testing
Transverse Rupture Strength (TRS) Testing is commonly performed on cemented carbides - a combination of fine particles mixed into a composite with a binder metal. They are sintered together by the application of pressure and heat which fuses the metal and other particles with higher melting points.
Cemented carbide was initially developed in Germany in the 1920s, to replace costly diamond as a material for machining metals. Carbide tooling offered an improvement in cutting speeds and feeds so remarkable that it forced machine tool designers to rethink every aspect of existing designs. The material's high hardness and wear resistance are applied in the crafting of cutting tools and dies, mining tools, rolls for use in mills producing steel tubes and bars, ball bearings, and pump pistons used in nuclear installations.
TRS specimens (usually a beam or rod) are evaluated using a controlled three-point bend test where an increasing load is applied on the center of the specimen until failure. The inside, or concave face of the bend, will see its maximum compressive stress while the outside, or convex face of the bend, will see the maximum tensile stress. The TRS is the determination of brittleness and toughness which is quantified by the maximum tension stress sustained prior to failure. Fracture strengths are dependent on internal or surface flaws in the material due to the high hardness values (typically 9-9.5 on the Mohs Scale and 2600 on the Vickers Scale). TRS is a means of determining the quality of the cemented carbide powder.
Common specifications that invoke this procedure include:
ASTM B406, the governing specification for the standard method of conducting transverse rupture strength testing
ASTM B578 - Standard Test Method for Transverse Rupture Strength of Powder Metallurgy (PM) Specimens
ISO 3327 - Hard Metals Determination of Transverse Rupture Strength
Manufacturer-specific documents and internal procedures
Entry Originally Posted May 2021