## 3 Results and Discussion
Although the temperature of #W511-7 is higher during the plasma discharge campaign, it does not lead to more cracks in the thermal load area, but rather only results in the widest crack. The generation of the widest crack releases most of the thermal stress, and thus, the crack density of #W511-7 is the lowest. Notably, #W511-11 has a recrystallization area and the deepest crack at the same time. The maximum crack length of #W511-14 is the shortest, and no recrystallization is observed in Figure 6c. The recrystallization of each monoblock is different due to the poloidal distribution of the heat load during plasma discharges, but #W511-11 and #W511-14 have similar short crack patterns, whereas the maximum crack lengths of #W511-7 and #W511-11 are the same. The maximum depth of such a crack is generally below 5 mm in all of the inspected W/Cu monoblocks. With this primary crack formation and propagation, the stress and strain concentration at the middle of the leading edge was thus alleviated. After that, new stress and strain concentrations will occur in the middle of the two isolated sections separated by the primary crack, giving rise to secondary cracks [23]. Figure 4: **(a)** Monoblock view direction (the viewing direction is shown by the arrow, and the viewing area is shown by the circle); **(b)** H-W plane of the metallographic picture of #W511-7; **(c)** H-W plane of the metallographic picture of #W511-11; **(d)** H-W plane of the metallographic picture of #W511-14. Figure 5: _Cont._  
The grain size was statistically analyzed, as shown in Figure 8. Most of the grains are below 50 \(\upmu\)m, whereas there are some large grains larger than 100 \(\upmu\)m. In #W511-7, there are some grains with a larger aspect ratio than in #W511-11 and #W511-14, which indicates the inhomogeneity of the deformed state. #W511-11 has a slightly larger aspect ratio, and more small grains of about 50 \(\upmu\)m are more significantly found than those of #W511-14. In #W511-14, due to the selection of the region, the statistical number of the grain is smaller, as most grain sizes are less than 50 \(\upmu\)m and the aspect ratio is generally smaller. The difference in grain size and aspect ratio reflects the inhomogeneity of the initial structure, which may be another reason for the difference in crack behavior. However, it can be observed in Figure 3d that on #W511-14, some equiaxed grains are visible on the leading edge near #13, but they cannot be seen near #15. The view of the grain boundary map of #W511-14 from another direction (Figure 9a) is shown in Figure 9b. Several recrystallized grains appear in the view of the H-W plane of #W511-14 from this direction near #W511-13. In Figure 6c, no obvious recrystallized grains are found, which indicates that the inhomogeneous heat flux is distributed along the T direction. Maybe this is related to the distribution of plasma strike points in EAST. Figure 5: (**a**) Monoblock view direction (the viewing direction is shown by the arrow, and the viewing area is shown by the circle); (**b**) grain orientation of #W511-7; (**c**) grain orientation of #W511-11; (**d**) grain orientation of #W511-14. Figure 4.0 _Cont._  
Figure 4.1 Comparison of recrystallization and crack damage in different monoblocks. Figure 4.2 Equivalent circle diameter and grain aspect ratio: (**a**) #W511-7; (**b**) #W511-11; (**c**) #W511-14. Figure 4.3 (**a**) Monoblock view direction (the viewing direction is shown by the arrow, and the viewing area is shown by the circle); (**b**) grain orientation of #W511-14. The temperature of #W511-14 is close to the recrystallization temperature, resulting in a gradient distribution of recrystallized grains along the T direction. This shows that the total length of the monoblocks above the recrystallization temperature is at least 70 mm along the T direction from #W511-7 to #W511-13; when considering the recrystallization in #W511-14, the actual length of recrystallization may be longer.