skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Tensile deformation and fracture properties of a 14YWT nanostructured ferritic alloy

Abstract

Here, a new larger heat of a 14YWT nanostructured ferritic alloy (NFA), FCRD NFA-1, was synthesized by ball milling FeO and argon atomized Fe-14Cr-3W-0.4Ti-0.2Y (wt%) powders, followed by hot extrusion, annealing and cross rolling to produce an ≈10 mm-thick plate. NFA-1 contains a bimodal size distribution of pancake-shaped, mostly very fine scale, grains. The as-processed plate also contains a large population of microcracks running parallel to its broad surfaces. The small grains and large concentration of Y–Ti–O nano-oxides (NOs) result in high strength up to 800 °C. The uniform and total elongations range from ≈1–8%, and ≈10–24%, respectively. The strength decreases more rapidly above ≈400 °C and deformation transitions to largely viscoplastic creep by ≈600 °C. While the local fracture mechanism is generally ductile-dimple microvoid nucleation, growth and coalescence, perhaps the most notable feature of tensile deformation behavior of NFA-1 is the occurrence of periodic delamination, manifested as fissures on the fracture surfaces.

Authors:
 [1];  [1];  [1];  [2];  [3];  [1]
  1. Univ. of California, Santa Barbara, CA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1330546
Grant/Contract Number:
AC05-00OR22725; FG03-94ER54275; #00119430 8-442520-59048
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing
Additional Journal Information:
Journal Volume: 675; Journal Issue: C; Journal ID: ISSN 0921-5093
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; nanostructured ferritic alloy; nano oxide; delamination; tensile properties; fractography

Citation Formats

Alam, M. Ershadul, Pal, Soupitak, Fields, Kirk, Maloy, S. A., Hoelzer, David T., and Odette, George R.. Tensile deformation and fracture properties of a 14YWT nanostructured ferritic alloy. United States: N. p., 2016. Web. doi:10.1016/j.msea.2016.08.051.
Alam, M. Ershadul, Pal, Soupitak, Fields, Kirk, Maloy, S. A., Hoelzer, David T., & Odette, George R.. Tensile deformation and fracture properties of a 14YWT nanostructured ferritic alloy. United States. doi:10.1016/j.msea.2016.08.051.
Alam, M. Ershadul, Pal, Soupitak, Fields, Kirk, Maloy, S. A., Hoelzer, David T., and Odette, George R.. 2016. "Tensile deformation and fracture properties of a 14YWT nanostructured ferritic alloy". United States. doi:10.1016/j.msea.2016.08.051. https://www.osti.gov/servlets/purl/1330546.
@article{osti_1330546,
title = {Tensile deformation and fracture properties of a 14YWT nanostructured ferritic alloy},
author = {Alam, M. Ershadul and Pal, Soupitak and Fields, Kirk and Maloy, S. A. and Hoelzer, David T. and Odette, George R.},
abstractNote = {Here, a new larger heat of a 14YWT nanostructured ferritic alloy (NFA), FCRD NFA-1, was synthesized by ball milling FeO and argon atomized Fe-14Cr-3W-0.4Ti-0.2Y (wt%) powders, followed by hot extrusion, annealing and cross rolling to produce an ≈10 mm-thick plate. NFA-1 contains a bimodal size distribution of pancake-shaped, mostly very fine scale, grains. The as-processed plate also contains a large population of microcracks running parallel to its broad surfaces. The small grains and large concentration of Y–Ti–O nano-oxides (NOs) result in high strength up to 800 °C. The uniform and total elongations range from ≈1–8%, and ≈10–24%, respectively. The strength decreases more rapidly above ≈400 °C and deformation transitions to largely viscoplastic creep by ≈600 °C. While the local fracture mechanism is generally ductile-dimple microvoid nucleation, growth and coalescence, perhaps the most notable feature of tensile deformation behavior of NFA-1 is the occurrence of periodic delamination, manifested as fissures on the fracture surfaces.},
doi = {10.1016/j.msea.2016.08.051},
journal = {Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing},
number = C,
volume = 675,
place = {United States},
year = 2016,
month = 8
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • Cited by 1
  • High temperature tensile fracture behavior has been characterized for the ferritic alloy 14YWT (SM10 heat) with the composition of Fe-14Cr-3W-0.4Ti (in wt.%) and strengthened by dispersion of nanometer-sized oxygen, titanium, and yttrium rich clusters. Tensile tests were performed at various temperatures ranging from room temperature to 1000 C in a vacuum condition using a nominal strain rate of 10-3s-1. Comparing with the existing oxide dispersion strengthened (ODS) steels such as Eurofer 97 and PM2000, the nanostructured alloy showed much higher yield and tensile strength over the test temperature range, but with lower elongation. Microstructural characterization for fractured tensile specimens wasmore » focused on the details of fracture morphology and mechanism to provide a feedback for process improvement. Below 600 C, the fracture surfaces exhibited a quasi-ductile behavior presented by a mixture of dimples and cleavage facets. At or above 600 C, however, the fracture surfaces were fully covered with dimples. The spherical particles that seemed to be oxide or carbide particles were found inside of dimples. It was notable that numerous microcracks were observed on the side surface of broken specimens. Formation of these microcracks is believed to be the main origin of the poor ductility of 14YWT alloy. It is suggested that any grain boundary strengthening measure is essential to improve the fracture property of the alloy.« less
  • This paperpresentsexperimentalresultsonthemechanicalandmicrostructuralbehaviorsofthe nanostructuredferriticalloy14YWTandprovidesdiscussionrelevanttodeformationmechanismsover a widerangeoftemperature.Thetemperaturedependenceofstrengthwasinvestigatedoverawide temperaturerangeof 196 to1000 1C. Detailedmicrostructuralcharacterizationbeforeandafter deformationwasconductedtoobtainthekeyinformationondeformationmechanisms;microstruc- tural informationbeforeandaftertensiledeformation,includingcrystallographictexture,dislocation structures,andnanoclusters,wasobtainedfromthefocusedionbeamlift-outspecimensusingEBSD, TEM, andAPTtechniques.Multipledeformationstagescouldbeidentifiedintheyieldstrengthversus temperaturecurve.Thedislocationstructuresinthespecimensdeformedatroomtemperatureandat 900 1C werefoundtobesignificantlydifferent.EBSDresultswereusedtoelucidatechangesinthe crystallographictexturesofthespecimensbeforeandafterdeformationat900 1C.