WELLHEAD PROFILE WITH INCREASED FATIGUE RESISTANCE

A wellhead includes a wellhead body and a locking end coupled to the wellhead body. The locking end includes an exterior surface with an exterior locking profile. The exterior locking profile includes an exterior groove formed between exterior stab and load flanks on the exterior surface. The locking end also includes an interior surface having an interior locking profile. The interior locking profile includes an interior groove formed between interior stab and load flanks on the interior surface. At least one of the exterior groove or the interior groove is a relief groove that undercuts at least one of the respective stab or load flank. The relief groove corresponds to a portion of the contour of an ellipse intersecting at least a portion of the respective stab or load flank, and an axis of the ellipse is at a tilted angle with respect to an axis of the wellhead.