Intrinsic, closure-free, threshold stress intensity, ΔK_th,i, is uniquely related to a certain computable near-tip residual stress, σ*; σ* is sensitive to applied stress ratio at given K_max under constant-amplitude loading and, particularly so, to load history under variable-amplitude loading. ΔK_th,i will vary significantly, depending on load conditions, rendering its characterization under controlled σ* crucial. Experiments on additive manufactured (AM) PH1 steel and 18Ni300 maraging steel confirm the possibility of characterizing the relationship between ΔK_th,i and σ* using small-size compact tension, C(T), specimens. This opens the way for material characterization from miniature specimens cut out from smaller components. Application of the relationship between ΔK_th,i and σ* leads to improved assessment of the structural integrity of AM components through residual crack growth analysis as well as specification of allowable defect size. It can serve as an input for optimization of AM process parameters.