Presentation Information
[1G08]In situ WB-STEM observation of crack tips on the Sharpy fracture surface of A533B steels
*Kenta Yoshida1, Hotaka Miyata1, Daisaku Yokoe2, Takeharu Kato2, Minako Endo3, Yuya Hideki3, Yusuke Shimada4, Hideo Watanabe4 (1. Tohoku Univ., 2. Japan Fine Ceramics Center, 3. Chubu Electric Power Co. Inc., 4. Kyushu Univ.)
Keywords:
RPV,Dislocation,TEM,In-situ
In this study, the Charpy impact test was performed for mechanically introducing cracks in A533B steel. Then, in situ WB-STEM annealing tests were performed from room temperature to 600°C. The film was sampled from the strain site at the crack tip (EBSD-KAM value: 2.7°) via Focus ion beam-scanning electron microscopy (FIB-SEM), i.e., the inhomogeneous plastic deformation zone of dislocation density above 2.5 × 1016 /m2 formed by Mn precipitates. Results revealed thermal relaxation of local strain as high density dislocations deformed into new subgrain boundaries via the geometrically necessary dislocation network at control temperatures from 500°C to 550°C.