Crack growth properties of FBR structural materials at elevated temperature

Koi, Mamoru

Fatigue and creep crack growth data of SUS304 stainless steel, 2.25Cr-1Mo steel and Mod.9Cr-1Mo steel, which were accumulated in PNC in last several years, were treated as a data base. Average trend equations of crack growth rate were proposed and also statistical analysis was carried out. Finite Elements analysis of center cracked tensioned plate was performed and simplified prediction method of modified J-integral J'(C ) was developed. 0btained results are summerized as follows: (1)In all tested materials, fatigue crack growth rate and creep crack growth rate were successfully represented using cyclic J-integral range J and modified J-integral J', respectivery. (2)In all tested materials, meaningful difference of crack growth rate could not be detected between hot rolled plate and forged material, and also between base metal and welded material. (3)Averaged trend equations of fatigue crack growth rate and creep crack growth rate of all tested materials were proposed on the basis of power low with cyclic J-integral range and modified J-integral, respectively. (4)Assuming that the coefficient and exponent of the above power low obey joint normal distribution, statistical analysis of crack growth rate was carried out and relationship between variance and J, J' were obtained. (5)Simplified method was developed to predict modified J-integral of center cracked tensioned plate. Prediction results show good agreement with experimental results, and this fact suggests that J-integral evaluation method of 3-dimensional surface crack, which has been developed in PNC, has good prediction accuracy.