The Paton Welding Journal, 2014, №02



2014 №02 (01)

DOI of Article 10.15407/tpwj2014.02.02

2014 №02 (03)

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The Paton Welding Journal, 2014, #2, 12-23 pages

FATIGUE LIFE OF DEPOSITED REPAIR WELDS ON SINGLE-CRYSTAL HIGH-TEMPERATURE NICKEL ALLOY UNDER CYCLIC OXIDATION

A.F. BELYAVIN, V.V. KURENKOVA and D.A. FEDOTOV

RC «Pratt&Whitney-Paton». 68 Gorky Str., Kiev, Ukraine. E-mail: vkurenkova@pwpaton.com
 
 
Abstract
In modern gas-turbine units increase of gas working temperature leads to shortening of blade service life. For this reason their repair becomes a priority. Retailoring of single-crystal blade tip by hardfacing is a rather complicated task. In order to select suitable filler material, thermal cycling tests of samples of deposited welds on CMSX-4 alloy with a single-crystal structure have been performed. Evolution of the structure under the conditions of high-temperature cyclic oxidation is considered. Selection of filler material, which ensures high temperature resistance and stability of weld metal structure, was optimized. These requirements are satisfied by Co-Ni-based material, which was earlier tried out and proved to be very good in complex technology of repair of a blade from ZMI-3U alloy. The technology includes airfoil tip retailoring by hardfacing with subsequent deposition on the item surface of a high-temperature metal coating by electron beam deposition to ensure the required service properties of the item. 18 Ref., 4 Tables, 10 Figures.
 
 
Keywords: single-crystal alloy, hardfacing, dendritic growth, stray grains, raft structure, heat-affected zone, cyclic oxidation, oxidation resistance, coating, spinel, yttrium oxide
 
 
Received:                25.10.13
Published:               28.02.14
 
 
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