ŠTAMBORSKÁ Michaela VSB - Technical University of Ostrava

Spoluautoři LOSERTOVÁ Monika, GALACZ Radek, KONEČNÁ Kateřina, HORSÁK Lukáš

The study of deformation distribution in tensile test specimens of IN 738 LC alloy was performed before and after hydrogenation. Tensile specimens were submitted to hot isostatic pressing before hydrogenation and tensile test. Half set of specimens was hydrogenated for 4 hours at 800 °C. Deformation rate of tensile test was of 0.025 s-1. Average yield strength of hydrogenated specimens reached of 76122 MPa that was by 5 % higher than for non-hydrogenated specimens. Average ultimate tensile stress decreased by 2 % to 90754 MPa. The analysis of mechanical properties and determination the strain fields obtained by digital image correlation for a tensile test was realized. During the tensile test was scanned surface of the specimen and observed displacement fields. From displacement fields were calculated strain fields by Vic 2D software and to enabled us to determine the hydrogen effect on the strains distribution and crack formation. The hydrogen content was measured using LECO RH600 analyser and ranges from 36 to 62 ppm. Hydrogen was found to affect the mode of fracture of superalloy samples. The fracture surfaces exhibited an increased amount of intergranular fracture due to the dissolved hydrogen, in case of transgranular cracking it was possible to observe an increasing amount of cleavage fracture with more secondary cracks.

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