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This work deals with the influence of hydrogen on the mechanical properties of TRIP 780 type C-Mn-Si steel. Tensile test bars were hydrogenated in 0.1N sulfuric acid solution with the addition of KSCN during the slow strain rate tensile tests (SSRT). Due to the presence of hydrogen in the steel microstructure, there was a significant decrease of elongation at fracture from 33 % to 3 % and a decrease of tensile strength from 868 MPa to 642 MPa, respectively 658 MPa at current density 5 or 1 mA•cm-2. The yield strength slightly increased from 505 MPa to approximately 517 MPa after hydrogenation. The relative change of elongation at fracture due to hydrogen was expressed by the index of hydrogen embrittlement F, which exceeded 95 %. The fracture surfaces of the tensile test bars were subjected to fractographic analysis. The presence of hydrogen during the tensile test influenced the failure mechanism and manifested itself by the occurrence of the quasi-cleavage fracture at the fracture surface.
Keywords: hydrogen embrittlement, TRIP steel, deformation, slow strain rate test (SSRT)© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.