• Ahmed, Hamdi Ahmed Elsayed
• Vallant, Rudolf
• Sommitsch, Christof
• Galler, M.

Abstract

Among different forms of environmentally assisted cracking (EAC), hydrogen embrittlement (HE), or more specifically, hydrogen induced stress corrosion cracking<br/>(HISCC) is the most critical form while dealing with high strength steel used for manufacturing of screws and fasteners(1). The downsizing trend of steel structures for<br/>mobility applications to increase the efficiency and decrease CO2 emissions faces this problem, as it is well known that increasing the steel strength also increases its<br/>susceptibility to HISCC. Thus, the screw strength class 10.9 (900 MPa yield and 1000 MPa tensile strength) is specified as the maximum for safety-related HISCC<br/>resistance(2). The main project goal is to establish a controllable method for HISCC testing, which should lead to a better understanding of the embrittlement<br/>mechanisms and to evaluate different microstructures, which are tempered martensite, bainite and pearlite by applying different heat treatments to achieve a tensile<br/>strength of 1400 MPa or higher. The HISCC testing procedure is performed as the Incremental Step Load Test (ISLT) according to standard ASTM F 1624(3) with in situ<br/>hydrogen charging by cathodic polarization and corrosion measurements.

Topics

• impedance spectroscopy
• microstructure
• mobility
• strength
• steel
• Hydrogen
• tensile strength
• susceptibility
• stress corrosion