High Temperature Degradation of Powder-processed Ni-based Superalloy

Natália Luptáková, Naděžda Pizúrová, Pavla Roupcová, Petr Dymáček

Abstract


The aim of present work is to study the high temperature degradation of the powder-processed polycrystalline superalloy Ni-15Cr-18Co-4Al-3.5Ti-5Mo. This superalloy has been applied as material for grips of a creep machine. The material was exposed at 1100 °C for about 10 days at 10 MPa stress. During the creep test occurred unacceptable creep deformation of grips as well as severe surface oxidation with scales peeling off. Three types of the microstructure were observed in the studied alloy: (i) unexposed state; (ii) heat treated (annealing - 10 min/1200 °C) and (iii) after using as a part of the equipment of the creep machine during the creep test. It is shown that the microstructure degradation resulting from the revealed γ´ phase fcc Ni3(Al,Ti) particles preferentially created at the grain boundaries of the samples after performing creep tests affects mechanical properties of the alloy and represents a significant contribution to all degradation processes affecting performance and service life of the creep machine grips. Based on investigation and obtained results, the given material is not recommended to be used for grips of creep machine at temperatures above 1000 °C.


Keywords


powder materials, polycrystalline Ni-based superalloy, creep machine grips, oxidation

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References


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Copyright (c) 2015 Natália Luptáková, Naděžda Pizúrová, Pavla Roupcová, Petr Dymáček

License URL: http://creativecommons.org/licenses/by-nc-nd/3.0/

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