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280mm t); ; Yoshida, Eiichi;
PNC TN9410 91-099, 106 Pages, 1991/02
This stady was performed in order to confirm the influence of sampling method on Creep properties of 9Cr-Mo steel forgings which are promising as candidate materials for steam generator of large scale fast breeder reactor. This results are to be reflected on fundation of materials strength standard. Test materials are four kinds of 9Cr-Mo steel forgings (thickness:250280mmt) such as Mod.9Cr-1Mo (F4, F8 heats), 9Cr-1Mo-Nb-V(G3 heat), 9Cr-2Mo (H6 heat) steels. Results obtained are summarized as follows. (1)In order to evaluation of fundamental material properties, creep-rupture data on three kinds of 9Cr-Mo steel forgings such as Mod.9Cr-1Mo, 9Cr-2Mo and 9Cr-1Mo-Nb-V steels was obtained up to 10,000 hours. (2)The Mod.9Cr-1Mo steel exhibited most excellent creep-rupture strength and the 9Cr-2Mo steel was the worst among the three. (3)The effect of the sampling location of specimens on creep strength was not significant for Mod.9Cr-1Mo steel. But for 9Cr-1Mo-Nb-V steel and 9Cr-2Mo steel, longer creep rupture time was observed with spcimens taken from just below the center of the surface with direction of L, and shorter creep rupture time was observed for those taken from t/2 thickness at the center with direction of Z. (4)Creep strength of 9Cr-2Mo steel was lower than that of Mod.9Cr-1Mo (F4, F8)and 9Cr-1Mo-Nb-V steel. But rupture elongation and reduction of area of 9Cr-2Mo steel was greater than hat of other three materials, irrespective of the sampling location of specimens.
Koi, Mamoru
PNC TN9410 90-105, 163 Pages, 1990/07
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.
