Minimum Transverse Rupture Strength (TRS)
The transverse rupture strength (TRS) of Tungsten Carbide with Cobalt variations is sometimes regarded as an indication of “toughness” which increases as hardness decreases. A recent study was conducted using a controlled group of Tungsten Carbide with Cobalt samples with consistent TRS values. It demonstrated a different relationship between the TRS and hardness of Tungsten Carbide with Cobalt compounds.
“It was shown that TRS is closely related to the hardness and facture toughness. Within a hardness range of 800 < Hv < 1500 kg/mm2, TRS appears to first increase and then decrease as the hardness increases. It reaches a peak value at Hv ≈ 1300 kg/mm2.” Zhigang Zak Fang 2004.
TRS is a measure of the strength of Tungsten Carbide. Tensile strength is not used on tungsten carbide because it is too brittle and accurate readings cannot be obtained. As a rule of thumb the tensile strength of tungsten carbide is approx. half of the transverse rupture strength.
Transverse rupture strength values are determined by the amount of force needed to break standard test pieces under the same test conditions.
Compressive strength is measured by compressing a right cylinder test piece between two tungsten carbide blocks held in line by an outer sleeve assembly. The CS of Tungsten Carbide is higher than for virtually all metals and alloys. This high compressive strength makes it possible to compress carbon at one million P.S.I. from man-made diamonds.
This measures the resistance of Tungsten Carbide to shock loading by a drop weight impact test. This is a more reliable indication of toughness than TRS readings.