タングステン合金の強度と破壊形態

Abstract

Static and dynamic tensile tests for sintered tungsten alloys having various volume fractions of tungsten particles were carried out in order to investigate the effects of volume fraction of tungsten, loading rate and mean diameter of tungsten grain on the mechanical properties. Both the Young's modulus and the yield strength increased with increasing volume fraction of tungsten. The tensile strength became maximum at the tungsten volume fraction of 90%. The true fracture stress, elongation and true fracture strain were reduced with increasing volume fraction of tungsten. However, these mechanical properties were scarecely influenced by the mean diameter of tungsten grain in the range from 30.5μm to 39.4μm. Although the yield and tensile strengths varied a little in the strain rate lower than 1.0s-1, they increased remarkably with increasing strain rate in the strain rate region higher than 1.0s-1. According to SEM observation, the cleavage fracture facets increased with increasing fracture strain.