Physics‐Constrained Decomposition of Accumulated Fatigue‐Life Deviations After Static Residual‐Stress Correction in Welded Compact‐Tension Specimens

Welding residual stress alters crack‐tip driving forces, complicating fatigue crack‐growth life assessment. Static corrections may leave systematic life deviations that are difficult to interpret. This study develops a physics‐constrained framework for diagnosing and decomposing these deviations in welded compact‐tension specimens. Two as‐welded specimens are assessed against a low‐residual‐stress reference from two post‐weld heat‐treated specimens. A logarithmic ratio of predicted to measured accumulated cycle increments quantifies deviations for hierarchical analysis. Relative to static correction, the residual‐stress‐pattern term reduces mean absolute deviations by 68.9% and 69.5% for A1–1 and A2–1, respectively. A closure/shielding‐related auxiliary term further reduces the deviations to 0.0538 and 0.0346 but exhibits greater boundary sensitivity. The prescribed functional form accommodates both specimens with different amplitudes, whereas direct parameter transfer increases error. The framework provides a diagnostic basis for evaluating the limitations of static residual‐stress correction.