13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- Table 1. Chemical composition of P92 steel in wt. % Table 2. Process parameters of multi-layer GTA welding C Si Mn P S Cr 0.09 0.16 0.47 0.01 0.001 8.72 Mo W V Nb B N 0.45 1.87 0.21 0.06 0.002 0.05 groove single bevel 20o preheating >373K welding current 200～250A arc voltage 10～10.5V welding speed 1.2～1.5mm/s multi-layer 33～37pass (a) The geometry and size of a circular notched specimen for weldment (b) Circular notch located in the middle part of HAZ (c) Circular notch located in the interface between base metal and fine-grained HAZ Figure 2. The geometry and size of a circular notched specimen for weldment and variation in the notch location in HAZ W Added 9Cr Steel (Welded Joint) CNS Notch located in the middle part of HAZ T=625oC, Kin=10MPam1/2, Creep Notch located to fine-grained HAZ Crack length Δa, mm Time, hr 0 200 400 600 800 0.25 0.5 0.75 W Added 9Cr Steel (Welded Joint) CNS T=625oC, K in=10MPam1/2, Creep Time, hr Load line displacement Δδ, mm Notch located in the middle part of HAZ Notch located to fine-grained HAZ 0 200 400 600 800 0.25 0.5 Figure 3. Characteristic of creep crack length Figure 4. Characteristic of load line displacement Notched to HAZ Notched to FG‐HAZ
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