Increasing Corrosion Fatigue of Welded Joints of Steel 15KhSND with Construction Defects by Electric Discharge Surface Alloying and High Frequency Mechanical Impact
V. V. Knysh$^{1}$, B. N. Mordyuk$^{2}$, G. I. Prokopenko$^{2}$, S. A. Solovey$^{1}$
$^{1}$E. O. Paton Electric Welding Institute, NAS of Ukraine, 11 Kazymyr Malevych Str., UA-03150 Kyiv, Ukraine
$^{2}$G. V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
Received: 01.08.2019. Download: PDF
The effects of combined hardening methods, including high-frequency mechanical impact (HFMI) using an ultrasonic tool and electric discharge surface alloying (EDSA) by nickel and chromium, on the cyclic durability of T-weld welded joints of low-alloyed 15KhSND steel in air and in a corrosive environment are studied. The results of fatigue tests of T-shaped welded joints are given, in the manufacture of which a construction defect was laid — the weld seam root is not fully melted along the entire length of the welded joint. As established, the cyclic durability of T-welded joints hardened by HFMI technology and containing construction defects (lack of melting of the weld seam root) is within the range of experimental data of the hardened welded joints made with full weld seam melting. In this case, the durability is increased by an order of magnitude as compared with the non-hardened samples. Studies of the fractures surfaces are carried out. The efficiency of application of the combined treatment of HFMI + EDSA (Cr) + HFMI to increase the characteristics of corrosion fatigue resistance of tee-welded joints is shown. After this treatment, the cyclic durability of samples tested in a corrosive environment is close to the durability of HFMI-hardened samples tested in air. As shown, the formation of the EDSA (Cr) layer, compared with EDSA (Ni), is more effective from the point of view of increasing the fatigue life in a corrosive environment, which is explained by the difference in the phase composition and integrity of the alloyed layers, as well as by the difference in electrochemical potentials of Ni and Cr in relation to Fe.
Key words: high-frequency mechanical impact, electric discharge surface alloying, cyclic durability, corrosion, welded joint, construction defects.
URL: http://mfint.imp.kiev.ua/en/abstract/v41/i12/1631.html
DOI: https://doi.org/10.15407/mfint.41.12.1631
PACS: 46.50.+a, 62.20.M-, 81.20.Vj, 81.40.Np, 81.65.-b
Citation: V. V. Knysh, B. N. Mordyuk, G. I. Prokopenko, and S. A. Solovey, Increasing Corrosion Fatigue of Welded Joints of Steel 15KhSND with Construction Defects by Electric Discharge Surface Alloying and High Frequency Mechanical Impact, Metallofiz. Noveishie Tekhnol., 41, No. 12: 1631—1652 (2019) (in Russian)