Hydrogen-Induced Ductility Loss in Cast Irons

Teruki Usuda; K. Matsuno; Hisao Matsunaga; Keiji Yanase; Masahiro Endo

doi:10.4028/www.scientific.net/MSF.750.260

Paper Titles

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Nanopore Formation on SOI(100) by CH₃SiH₃ Pulse Jet CVD: SiC Growth Temperature Dependence
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Estimation for Fatigue Behavior of Notched Plate with Mean Stress Effect
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Hydrogen-Induced Ductility Loss in Cast Irons
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Effect of Occasional Shear Loading on Fatigue Crack Growth in 7075 Aluminum Alloy
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Effect of Dry-Ice Blasting on the Microstructure and Properties of Plasma-Sprayed CoNiCrAlY Coating
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Morphology and Residual Stress of Ultrathin Al Films Confined by AlN Layers
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A High Sensitivity 3-D Measurement Method of Minute Specimen Based on Microscope and Laser Projection
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HomeMaterials Science ForumMaterials Science Forum Vol. 750Hydrogen-Induced Ductility Loss in Cast Irons

Hydrogen-Induced Ductility Loss in Cast Irons

Abstract:

Effect of hydrogen-charging was investigated with respect to the tensile properties of three types of cast irons: JIS FCD400, FCD450 and FCD700. In this study, hydrogen charging led to a marked ductility loss in all the cast irons. The thermal desorption spectroscopy and the hydrogen microprint technique revealed that, in the hydrogen-charged specimens, most of solute hydrogen was diffusive and mainly segregated at graphite, graphite/matrix interface zone and pearlite. In the fracture process of non-charged specimen, neighboring graphites were interconnected with each other mainly by ductile dimple fracture. On the other hand, in the fracture process of hydrogen-charged specimen, the graphites were interconnected by cracks. The difference in the fracture morphology between the non-charged and the hydrogen-charged specimens is attributed to the presence of diffusive hydrogen in graphite and graphite/matrix interface. During early stage of fracture process in hydrogen-charged specimen, the interspace between graphite and matrix is filled with hydrogen gas, which leads to the ductility loss of matrix in the vicinity of graphite. Even after the initiation of crack from graphite, hydrogen is continuously outgassed from graphite and supplied to the crack tip. Therefore, concerning the hydrogen effect on the strength of cast irons, a role of subsurface graphite as a “local hydrogen supplier” should be taken into consideration.