Fatigue Crack Propagation and Fracture Studies of a Pressure Vessel Steel Temper Embrittled to Simulate Irradiation Damage

摘要

Fatigue crack propagation tests were conducted using plate bend specimens machined from shell material of the PM-2A half-scale model pressure vessel. The material is a Cr-Mo-V rotor steel, temper embrittled to represent the irradiated shell of the PM-2A reactor vessel. The fatigue tests were conducted in a room-air environment at 80 F, which is 160 F below the NDT (nil-ductility transition) temperature for this steel. Fatigue crack growth rates were correlated with total strain range, and were found to be similar to fatigue crack growth rates in other structural steels which possess comparable yield strength levels. Fracture occurred in the plate bend specimens of the test material during fatigue cycling. This represents a significant departure from the behavior of previously studied structural steels, and is attributed to the very high NDT temperature of the test material. An analysis of the fractures using an approximate solution for the stress-intensity factor, K, gave good agreement with previous plane strain fracture toughness measurements on the test material. (Author)