DIFFUSION WELDING IN VACUUM THIN SHEET OF NICKEL ALLOY

Author:

Falchenko Yurii, Paton Electric Welding Institute of NAS of Ukraine (11 Bozhenko Str., 03680 Kiev, Ukraine)

Petrushynets Lidiia, Paton Electric Welding Institute of NAS of Ukraine (11 Bozhenko Str., 03680 Kiev, Ukraine)

Ustinov Anatolii, Paton Electric Welding Institute of NAS of Ukraine (11 Bozhenko Str., 03680 Kiev, Ukraine)

Melnichenko Tatiana , Paton Electric Welding Institute of NAS of Ukraine (11 Bozhenko Str., 03680 Kiev, Ukraine)

Novomlinets Oleg, Chernihiv National University of Technology (95 Shevchenka Str., 14027 Chernihiv, Ukraine)

Gusarova Irina, M. K. Yangel Yuzhnoye State Design Office (3 Krivorozhskaya Str., 49008 Dnipro, Ukraine).

Language: ukrainian

Annotation:

Urgency of the research. Nickel alloys are widely applied in manufacture of gas turbines, in space vehiclesrocket engines, etc.

Target setting. Complexity of producing nickel alloy joints by diffusion welding consists in presence of a thermally-stable oxide layer on their surfaces and low ductility of this group of materials.

Actual scientific researches and issues analysis. Performed analysis showed that combination of high parameters of diffusion welding with application of interlayers allows producing sound joints ofhigh-temperature nickel alloys.

Uninvestigated parts of general matters defining. Described technologies are designed for joining massive items and are not suitable for thin foils.

The research objective. Study the possibility of producing welded joints of foils of powdered nickel alloys.

The statement of basic materials. Vacuum diffusion welding of nickel foils of thickness δ = 25 μm was performed.

In welding without interlayers the defectiveness of the joint zone is reduced with increase of welding temperature. However, even at Тw = 1200 °С a string of oxides and pores in the joint zone is preserved.

Cu, Co, Ni interlayers were used for activation of diffusion processes. Application of interlayers with Co leads to formation of chemical inhomogeneity in the joint zone and development of considerable porosity in the butt. Application of Ni interlayers leads to formation of a zone with a low chromium content in the butt zone. Microstructure of this zone is similar to that of the initial alloy, but is less defective. Welding with Cu interlayer ensures a uniform nature of distribution of elements in the butt and minimum number of defects.

Average strength of samples produced with Ni interlayer is equal to σв = 108 MPawith Co  σв = 233 MPaand with Cu – σв = 317 MPa.

Conclusions. Conditions for producing joints of thin foils of a nickel alloy by vacuum diffusion welding at application of Cu, Co, Ni interlayers were studiedIt is shown that foils produced by thetechnology of electron beam evaporation and condensation in vacuum promote intensification of diffusion processes in the butt and ensure formation of welded joints.

Key words:

diffusion welding in vacuum, Ni-Cr, multilayer foil, microstructure, microindentation

References:

1. Sims, Ch.T., Stoloff, N.S. & Xagsel, U.K. (eds.) (1995). Supersplavy II: Zharoprochnye materialy dlia aerokosmicheskikh i promyshlennykh energoustanovok [Superalloys: materials for aerocosmic and industrial energyequipment]. Book 1. Moscow: Metallurgija (in Russian).

2. Atkinson, H.V. (1985). A Review of the Role of Short-Circuit Diffusion in the Oxidation of Nickel, Chromium, and Nickel–Chromium Alloys. Oxidation of Metals, vol. 24, № 3/4, pp. 177–197.

3. Yeh, M.S., Chang, C.B., Chuang, T.H. (2000). Diffusion Bonding of a Superplastic Inconel 718SPF Superalloy by Electroless Nickel Plating. Journal of Materials Engineering and Performance, vol. 9, pp. 51–55.

4. Musin, R.A., Anciferov, V.N., & Kvasnickij, V.F. (1979). Diffuzionnaia svarka zharoprochnykh splavov [Diffusion welding of heatproof alloys]. Moscow: Metallurgiia (in Russian).

5. Methods for Diffusion Welding the Superalloy Udimet 700 (1972). Welding Research Supplement, vol. 2, pp. 41–49.

6. Harchenko, G.K., Ustinov, A.I. & Falchenko, Iu.V. (2011). Diffuzionnaia svarka v vakuume splava na osnove γ-TiAl s ispolzovaniem nanosloinykh prosloek [Diffusion welding in alloys` vacuum based on γ-TiAl with the usage of nanolayer layers] Avtomaticheskaia svarka – Automatic Welding, no. 3, pp. 7–11 (in Russian).

7. Ustinov, A.I., Liapina, K.V. & Melnichenko, T.V. (2005). Zakonomernosti formirovaniia poristoi struktury nerzhavejushhej stali pri ee osazhdenii iz parovoi fazy v prisutstvii parov khloristogo natriia [Regularity of formation of porous structure of stainless steel over its sedimentation with vapours of muriate of soda]. Spec. Elektrometallurgiia, no. 4, pp. 23–28 (in Russian).

8. Firstov, S.A., Gorban, V.F. & Pechkovskii, E.P. (2007). Uravnenie indentirovaniia [Equation of indentation]. Dopovіdі Nacіonalnoi akademіi nauk Ukrainy, no. 12, pp. 100–106 (in Russian).

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