Defect density (prior hardening) plays a large role in determining how much energy is absorbed by a material via dislocation motion prior to fracture. High point and line defect densities reduce dislocation mobility and thus the energy absorbed to fracture, resulting in lower measures of fracture toughness (K_Jc or J_Ic). For any given material, there is a maximum load condition (defined as dσ/dɛ = σ) that coincides with the engineering ultimate tensile stress at which deformation transitions from bulk movement of dislocations to local growth of voids or cracks. This suggests that there is a maximum defect density that can be accumulated in a material prior to the onset of fracture and that any measure of energy absorbed to fracture (e.g., Charpy or fracture toughness) will saturate as hardening increases. The idea of a maximum defect density implied by the maximum load condition suggests that the unirradiated defect density should be accounted for when trying to predict the effects of irradiation on subsequent measures of irradiated toughness. Unirradiated yield strength provides one possibility to account for initial defect density (prior hardening) on the effects of subsequent irradiation hardening. Tensile, Charpy, and fracture toughness data are used to investigate this prior hardening idea.