Mechanical properties of three kinds of ITER-Grade pure tungsten with different manufacturing processes

Abstract

• The Vickers hardness test results showed no significant data dispersion. • Micro pillar test results were some data dispersion identified in both the center and the near-surface. • The tensile test showed comparably large data dispersion. • Weak defect structure may complicate the cracks, resulting in the data dispersion. Pure tungsten plates with three kinds of manufacturing processes, i.e., ITER-Grade tungsten, cross-rolled tungsten with a moderate rolling ratio and another cross-rolled tungsten with a high rolling ratio, were evaluated by the Vickers hardness test, tensile test at room temperature and 500 °C, and micro pillar test. The Vickers hardness test results showed that the hardness value of all types of the tungsten plates was 410–430 Hv and no significant data dispersion was identified. However, the tensile test showed comparably large data dispersion, which was particularly drastic at room temperature. In parallel, to determine the effect of the specimen cut location thorough the plate thickness direction (S-Direction), micro pillar tests were conducted. Although there were some data dispersion, test results showed plastic deformation and no marked effect of the cut location was identified. It is therefore believed that the specimen cut location did not affect the data dispersion identified in the tensile test. Alternatively, the probable explanation for such large dispersion is partial detachment of the surface bulk structure. Such specific microstructure can make crack paths more complicated, resulting in the data dispersion.