Cracking and grain refining behaviors of tungsten based plasma facing materials under fusion relevant transient heat flux

To investigate the behaviors of tungsten based plasma facing materials under fusion relevant transient heat flux, two kinds of commercial tungsten materials processed with and without rolling respectively, have been tested on the EMS-60 facility using 0-800 MW/m2 with single pulse duration of 5 ms. The macro and micro cracks were observed as expected, whose distribution patterns were depicted and explained by the residual stress distribution analysis with the finite element method. Moreover, when high heat flux exceeded 600 MW/m2 (∼5 ms), the refining of grain crystal occurred not only at the central area but also around the micro cracks.