Kobayashi, T., Somerday, B., San Marchi, C., & Nibur, K. A. (2009). CHARACTERIZATION OF HYDROGEN-ASSISTED FRACTURE MECHANISM BY FRACTURE SURFACE TOPOGRAPHY ANALYSIS (FRASTA). In Effects of Hydrogen on Materials: Proceedings of the 2008 International Hydrogen Conference, September 7-10, 2008, Jackson Lake Lodge, Grand Teton National Park, Wyoming, USA (p. 211). ASM International.
Abstract
The fracture surface topography analysis (FRASTA) technique was applied to the crack arrest threshold region in a wedge-opening-load (WOL) ASME SA 372 Grade J sample tested in hydrogen gas at 100 MPa. FRASTA juxtaposed and incrementally displaced conjugate fracture surface topographs to reconstruct microfracture processes, and displayed the results graphically. Although qualitative fracture surface examination revealed little evidence of intergranular cracking and did not show the precise fracture path with respect to the microstructure, FRASTA established the sequence of local microcrack formation, growth, and coalescence at the crack front. In addition, FRASTA was successful in determining the local crack opening displacement and assessing local fracture resistance.