The Paton Welding Journal, 2013, №05



2013 №05 (05)

2013 №05 (07)

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The Paton Welding Journal, 2013, #5, 45-50 pages  

INFLUENCE OF WELD POOL GEOMETRY ON STRUCTURE OF METAL OF WELDS ON HIGH-TEMPERATURE NICKEL ALLOY SINGLE CRYSTALS

K.A. YUSHCHENKO¹, I.S. GAKH¹, B.A. ZADERY¹, A.V. ZVYAGINTSEVA¹ and O.P. KARASEVSKAYA²

¹E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
²G.V. Kurdyumov Institute for Metal Physics, NASU, Kiev, Ukraine
 
 
Abstract
The main defect, which prevents realization of the advantages of high-temperature nickel alloy single crystals in production of welded assemblies and parts of gas-turbine engine, are stray grains in the weld metal. The objective of this work was studying the features of weld metal structure, depending on curvature of macrofront of weld pool solidification and determination of admissible deviations of the direction of maximum temperature gradient from orientation of predominant crystal growth. Experiments were performed with application of electron beam welding on single-crystal samples from commercial high-temperature nickel alloys JS26 and JS32, containing more than 60 % of strengthening γ`-phase. Welded joint structure was studied by optical metallography and X-ray diffractometry methods. It is shown that the main conditions for preservation of single-crystal structure in welding of high-temperature nickel alloy single crystals are correspondence of fusion plane to single crystal high-symmetry axes and coincidence of the direction of maximum heat removal over weld pool solidification front with <001> orientation of predominant crystal growth. Limit deviations for studied alloys and welding conditions are established. 15 Ref., 9 Figures.
 
 
Keywords: electron beam welding, single crystal, high-temperature nickel alloy, crystallographic orientation, weld, weld pool geometry, dislocation distribution, crystal growth direction, maximum heat removal direction, angle of deviation, stray grains
 
 
Received:                01.03.13
Published:               28.05.13
 
 
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