Fatigue Crack Growth Resistance of Several Neutron Irradiated Pressure Vessel Steels and Welds

Pre and postirradiation fatigue crack growth rates in A302-B, A533-B, and A543 steel plate and in two A543 welds (submerged arc and electroslag) were determined at 550 deg F (288 deg C) in air. The fracture mechanics approach was used to analyze the experimental data. Neutron irradiation at 585 deg F (307 deg C) to 2.5 × 10¹⁹ n/cm², > 1 MeV produced no significant effect on resistance to crack growth in A302-B steel and caused only a slight decrease in crack growth resistance of A533-B and A543 steels. Also, the resistance to crack growth of the submerged arc weld was unaffected by the irradiation, but that of the electroslag weld was substantially improved. The crack growth rate versus stress intensity factor range curve for the A302-B steel represents an upper bound for the pre and postirradiation data for the steels and welds of this study.