Performed tensile and fatigue tests on bolts to determine if cutting of materials flow lines at the bolt underhead would degrade bolt integrity. Five different alloys used in aerospace industry fatigue critical applications were employed to fabricate 5/16 to « inch diameter bolts. These bolts were machined from bar stock producing fully cut material flow lines under their heads. Tensile testing with and without underhead washers was performed along with industry standard fatigue testing.