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Indexed by:期刊论文

Date of Publication:2016-04-01

Journal:MATERIALS CHARACTERIZATION

Included Journals:SCIE、EI

Volume:114

Page Number:267-276

ISSN No.:1044-5803

Key Words:Electron beam smelting; Inconel 740; Microstructure; Vickers hardness; Deformation behavior

Abstract:Electron beam smelting (EBS) has been used to fabricate the Inconel 740 superalloy. Microstructures, hardness, and deformation characteristics of the alloy are studied. It is observed that carbides and fine secondary phase nuclei are distributed in the hot worked EBS 740 superalloy. The Ostwald ripening occurs during solution treatment and leads to aggregation of the gamma precipitates, the size of gamma' precipitates varies from several nanometers to more than one hundred nanometers as a result. The average size of the secondary phase is <30 nm after aging treatment and the average Vickers hardness is measured to be about 370. The critical shear stress is calculated to be 0.627 GPa with governing mechanism of shearing, causing a stronger strengthening effect than the traditionally prepared Inconel 740 superalloy. The compression behavior indicates that the EBS 740 superalloy shows higher flow stress than 740H at low Zener-Hollomon parameter, which may arise from the undissolved gamma' precipitates and higher activation energy 12 The tensile results show that the fracture surface exhibits a ductile fracture pattern, in contrast to no obvious plastic deformation on the macroscopic fracture. Crack propagation proceeds in a transgranular fracture mode with facets and voids presented on the fracture surface. (C) 2016 Elsevier Inc. All rights reserved.