Cracking failure study of ITER-reference tungsten grade under single pulse thermal shock loads at elevated temperatures

Crack formation in an ITER-reference tungsten grade was examined under single thermal shock loading. Typically two sorts of cracks, major cracks and microcracks, were observed at the loaded surfaces. The microstructures were quantified and the formation mechanisms were discussed. The major cracks were generated due to the brittleness of the tungsten material and microcracks were formed in a process which was initiated by plastic deformation at high temperature. The plastic deformation caused also surface elevation of the loaded area. At more intense thermal shock loading conditions, the microcracks disappeared and surface modifications due to recrystallization was observed.