Detection and Imaging of Damage, Including Hydrogen Embrittlement Effects in Landing Gear and Other High-Strength Steel Components

"Hydrogen embrittlement can occur in high-strength steel components as a result of hydrogen uptake during cleaning with acid-based solutions, plating, or pickling. Reliable nondestructive detection of hydrogen embrittlement effects in high-strength steelaircraft components has been identified as critical for safety and sustainment of U.S. Air Force aircraft. In Phase I, using both high-resolution MWM-Array imaging and permanently mounted MWM-Arrays, JENTEK demonstrated (1) sensitivity to hydrogenembrittlement, (2) small crack detection (less than 0.01-in.) in 4340 steel, (3) precrack fatigue detection and monitoring in a high-strength steel (suitable for failure likelihood prediction), (4) stress measurement, and (5) characterization of shotpeened steel through cadmium plating. These demonstrated capabilities establish the feasibility to detect and characterize microstructure variations associated with hydrogren embrittlement, estimate applied and residual stresses, and detect early stagecracking for critical landing gear components. The proposed capability enhancements for the Phase II research will provide an effective portable tool for laboratory, production, and field applications. In Phase II, JENTEK will develop robust, fieldableprocedures for detection of hydrogen embrittlement in high-strength steels."