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Indexed by:Journal Papers

Date of Publication:2015-07-25

Journal:JOURNAL OF ALLOYS AND COMPOUNDS

Included Journals:SCIE、EI、Scopus

Volume:638

Page Number:239-248

ISSN No.:0925-8388

Key Words:Solution treatment; Inconel 740; Electron beam smelting; Microstructure; Vickers hardness; gamma ' phase

Abstract:Electron beam smelting (EBS) was used to prepare the Inconel 740 superalloy. The microstructure and hardness of Inconel 740 were investigated both under hot working condition and followed by solution heat treatment under high temperature ranging from 1120 to 1210 degrees C for 30 min. The results show that fine gamma' nucleus and primary MC carbides exist in the hot working superalloy. With increasing temperature of solution treatment, TiNiSi phase is gradually solutionized into the matrix, whose volume fraction decreases exponentially. gamma' precipitates coarsening occurs at 1150 degrees C, while higher temperature solution treatment leads to the solution of gamma' precipitates. gamma '' phase has been found keeping a stringent coherent relationship with Nb0.03Ni3Ti0.97 phase at 1180 degrees C, and utterly transformed into Nb0.03Ni3Ti0.97 phase at 1210 degrees C. The hardness of the solution-treated superalloy is lower than that of hot working, the value decreases at first and then increases with increasing of solution temperature, which is attributed to dislocations interaction and localized shear stress caused by gamma' precipitates and local stress fields. (C) 2015 Elsevier B.V. All rights reserved.