Nickel-based alloys such as Alloy 600 and Alloy 690,and weld metals such as Alloys 182/2082/132/52/152 have been widely used in pressurized water reactor(PWR)components.Stress corrosion cracking(SCC)of nickel-base alloys and weld metals such as Alloys 600 and 182.Recently the reliability of Alloy 690 and its weld metals in PWR primary water is investigated.Electric Power Research Institute(EPRI)Materials Reliability Program(MRP)proposed a crack growth rate disposition curve in a report MRP 55 for primary water stress corrosion cracking(PWSCC)of thick section Alloy 600 materials.This CGR equation has been adopted by Section XI Nonmandatory Appendix O of the ASME Boiler & Pressure Vessel Code for flaw evaluation.MRP also proposed a CGR disposition curve in a report MRP 115 for PWSCC of Alloys 82/181/132 weld metals.The effects of stress intensity factor(K),temperature and thermal activation energy,and weld metal orientation have been included in the MRP 115 curve.One critical issue is the theoretical basis for introducing the effect of stress intensity factor in the crack growth rate formulation.T.Shoji et al has introduced the effect of mechanical parameters by using a crack tip strain rate parameter.In our newly developed deterministic approach for CGR formulation,a quasi-static crack tip asymptotic field and a quasi-solid state crack tip oxidation kinetics are incorporated.Finally,an exponential form of crack growth rate versus stress intensity factor is developed for PWSCC growth rates of Ni-base alloys and weld metals.The generated parameters by the newly developed equation are consistent with fitting parameters of the experimental data and the parameters used in the MRP 115 equation.The effects of other parameters such as water chemistry and temperature used in the newly developed crack growth rate equation are also consistent with the experimental observation for PWSCC of Ni-base alloys and weld metals.More fundamental data such as crack tip oxidation rate constants in terms of local mechanical,local environmental and local material parameters are required for predicting of stress corrosion cracking growth rate under complex conditions.