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Characterization of Nb Interface Segregation During Welding Thermal Cycle in Microalloyed Steel by Atom Probe Tomography

Version 2 2024-06-06, 08:46
Version 1 2018-10-19, 17:09
journal contribution
posted on 2024-06-06, 08:46 authored by HH Wang, J Wang, Z Tong, Peter HodgsonPeter Hodgson, XL Wan, KM Wu, R Wei, I Timokhina
Coarse-grained, welding heat-affected zone microstructure was simulated in a Nb-bearing microalloyed steel. The granular bainite with a great number of martensite-austenite (M-A) constituents was the predominant phase. Using atom probe tomography (APT), the distributions of niobium at prior austenite grain boundary (PAGB), ferrite/martensite-austenite (M-A) constituent interface (FMAI), and ferrite/ferrite interface (FFI) were investigated. The binding energy of Nb atom and vacancy was predicted to be 0.45 eV, indicating that Nb segregation by welding thermal cycle is probably a result of the nonequilibrium mechanism. The maximum enrichment of Nb was found at FMAI with enrichment factor of 3.50. Intermediate enrichment of Nb was at PAGB with enrichment factor of 3.12. The interfacial excess of Nb solute element ГNbat PAGB determined by APT was 0.27 × 1019atoms/m2. The segregation energy was calculated to be 22.91 kJ/mol. The minimum enrichment of Nb was at FFI with an enrichment factor of 1.80.

History

Journal

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

Volume

49

Pagination

6224-6230

Location

Cham, Switzerland

ISSN

1073-5623

eISSN

1543-1940

Language

English

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2018, The Minerals, Metals & Materials Society and ASM International

Issue

12

Publisher

SPRINGER