Effect and mechanism of out-of-plane constraint on creep crack growth behavior of a Cr–Mo–V steel

Prediction of creep crack growth behavior in Cr–Mo–V steel specimens with different constraints for a wide range of C∗

“…Some experimental and theoretical evidences have shown that the crack-tip constraint can affect creep crack growth (CCG) rates [1][2][3][4][5][6][7][8][9][10][11][12][13]. For a given C ⁄ value, CCG rates in plane strain (PE) are significantly greater than those in plane stress [2][3][4][5][6].…”

Creep constraint analysis and constraint parameter solutions for axial semi-elliptical surface cracks in pressurized pipes

“…If the C * of the cracked pipes is lower than that of the standard C(T) specimen under plane-strain, its creep crack growth rate will be much lower than that of the standard C(T) specimen. For the Cr-Mo-V steel, the creep crack growth rates at lower C * which is relative to actual high temperature components are more sensitive to the constraint effects [13,33,42]. Therefore, the excessive conservatism may be produced in creep life prediction of cracked pipes if the creep crack growth rate data of the standard C(T) specimen is used and the creep constraint effect cannot be considered.…”

“…For a given C ⁄ value (creep fracture mechanics parameter), the model predications showed that the CCG rates in plane strain (PE) are significantly greater than those in plane stress [7][8][9][10][11]. The experimental results of Tabuchi et al [12] and Tan et al [13,14] have shown that there is an effect of specimen thickness on the creep crack growth rate, and the specimens with larger thickness exhibit the higher creep crack growth rate. It also has been found that at the same C ⁄ value the creep crack growth rates measured in the middle tension (M(T)) specimens are lower than those obtained from deep crack compact tension (C(T)) specimens for the austenitic stainless steels [15][16][17] and ferritic steels [18].…”

“…Under creep conditions, a lot of experimental and theoretical evidences have shown that constraint can affect creep crack growth rate [6][7][8][9][10][11][12][13][14][15][16][17][18]. However, the deep crack and high constraint C(T) specimen data (R * = 0) measured by using standard test procedure [21] are conventionally used in creep crack growth assessments [41].…”

“…Under creep conditions, a lot of experimental and theoretical evidences have shown that constraint can affect creep crack growth (CCG) rate [6][7][8][9][10][11][12][13][14][15][16][17][18]. For a given C ⁄ value (creep fracture mechanics parameter), the model predications showed that the CCG rates in plane strain (PE) are significantly greater than those in plane stress [7][8][9][10][11].…”