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

Highlights: • The crack patterns were depicted on tungsten under fusion relevant transient heat flux using the EMS-60. • The generated mechanism for representative center and surrounding cracks was examined by FEM analysis on the thermal mechanical response. • The grain refining occurred not only at the central area but also around the micro cracks on tungsten surface when the transient heat flux exceeded 600 MW/m² (∼5 ms). - Abstract: 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.