Deformation and Fracture of Single Crystals of Heat-resistant Nickel Alloys with Welded Joints During Tensile Tests
O. P. Karasevska$^{1}$, K. A. Yushchenko$^{2}$, B. A. Zadery$^{2}$, I. S. Gakh$^{2}$, H. V. Zviagintseva$^{2}$, Т. O. Alekseenko$^{2}$
$^{1}$G. V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
$^{2}$E. O. Paton Electric Welding Institute, NAS of Ukraine, 11 Kazymyr Malevych Str., UA-03150 Kyiv, Ukraine
Received: 26.01.2021; final version - 21.05.2021. Download: PDF
The features of deformation and fracture in the temperature range of 500–1200°С under tension of samples of welded joints of heat-resistant nickel alloys single crystals are investigated. The joints are made by the electron beam method with a perpendicular (group 1) and parallel (group 2) weld location relative to the applied load. The values of tensile yield stress ($\sigma_{y}$), elongation ($\delta$) and the difference in the types of destruction in the low-temperature ($\leq$ 800°С) and high-temperature (> 800°С) test areas are established, which are mainly associated with the dispersion and defectiveness of the growth structure and the structure obtained in welds. Fracture in the 1$^{st}$ group of specimens, in the low-temperature region, occurs outside the weld along the growth structure of the single crystal, mainly by transcrystalline macroshear with a mixed nature of the fracture with the values of $\sigma_{y}$ lower by $\sim$ 15% than in the 2$^{nd}$ group. Samples of the 2$^{nd}$ group in the low-temperature region are destroyed along the interdendritic spaces with noticeable marks of plastic deformation; with an increase in temperature, the part of ductile fracture decreases and the part of interphase fracture increases, the fractures of which repeat the dendritic morphology of the weld structure. In the high-temperature region, the samples of the 1$^{st}$ group are destroyed according to the mechanism of brittle transcrystalline cleavage with multi-site nucleation along the interphase boundaries of the weld with higher values of $\sigma_{y}$ than in the 2$^{nd}$ group. The peculiarities of deformation are considered in connection with structural changes in welds in comparison with the growth structure of the initial heat-resistant nickel alloys single crystals.
Key words: single crystals of heat-resistant nickel alloys, structure of welded joints, temperature and deformation of destruction.
URL: https://mfint.imp.kiev.ua/en/abstract/v43/i07/0939.html
DOI: https://doi.org/10.15407/mfint.43.07.0939
PACS: 61.50.Ks, 61.66.Dk, 61.72.Dd, 62.20.M-, 81.20.Vj, 81.40.Np, 81.70.Bt
Citation: O. P. Karasevska, K. A. Yushchenko, B. A. Zadery, I. S. Gakh, H. V. Zviagintseva, and Т. O. Alekseenko, Deformation and Fracture of Single Crystals of Heat-resistant Nickel Alloys with Welded Joints During Tensile Tests, Metallofiz. Noveishie Tekhnol., 43, No. 7: 939—957 (2021) (in Ukrainian)