Measurement of G-phase volume fraction and number density in duplex stainless steels using transmission electron microscopy

Isak McGieson, Jonathan D. Poplawsky, Melissa K. Santala, Julie D. Tucker

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Duplex stainless steels (DSS) have a high toughness and strength due the presence of both austenitic and ferritic phases. These alloys have had limited use in power production applications due to thermal embrittlement caused by spinodal decomposition and development of G-phase precipitates in the ferrite. Lean grade DSS alloys (e.g., 2101, 2003) may offer improved thermal stability due to the reduction of Cr- and Ni-equivalent elements when compared to standard grade compositions (e.g., 2205, 2209). The abundance of the G-phase was measured in five duplex stainless steels, three wrought alloys (2101, 2003, 2205) and their matching filler metals (2101-w, 2209-w), after aging at 427 °C for 1000 h and 10,000 h. The G-phase volume fraction, number density, size, and precipitate spacing were found using quantitative analysis of transmission electron microscopy dark field images and the composition of G-phase precipitates on other clusters were characterized with atom probe tomography (APT). In the welded alloys, the G-phase was found to develop rapidly, relative to the wrought material. A positive correlation was found between the nickel equivalent composition of the alloy and the G-phase volume fraction. The alloys 2205, 2209, and 2101-w, which are higher in Cr and Ni, all showed significant G-phase precipitation, further strengthening the hypothesis that lean grade DSS alloys are more thermally stable against precipitation in the ferrite. Electron diffraction showed a secondary phase present in the 2101 wrought alloy at 10,000 h, but it was not crystallographically consistent with the G-phase; APT showed the presence of nanoclusters rich in both nickel and copper for this alloy. No secondary phases or clusters were found in 2003 after 10,000 h of aging, so it may be a candidate alloy for applications that require long-life times at high operating temperatures.

Original languageEnglish
Article number107926
JournalMaterials Today Communications
Volume38
DOIs
StatePublished - Mar 2024

Funding

This research was supported by the U.S. Department of Energy, Nuclear Energy University Programs under the grant DE-NE0008668 . TEM was performed at the Oregon State University Electron Microscope Facility ( EMF ) which is supported by NSF MRI Grant No. 1040588 , the Murdock Charitable Trust , and the Oregon Nanoscience and Micro-Technologies Institute . The authors gratefully acknowledge the technical assistance provided by the staff of the EMF (Dr. P. Eschbach). APT research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This research was supported by the U.S. Department of Energy, Nuclear Energy University Programs under the grant DE-NE0008668. TEM was performed at the Oregon State University Electron Microscope Facility (EMF) which is supported by NSF MRI Grant No. 1040588, the Murdock Charitable Trust, and the Oregon Nanoscience and Micro-Technologies Institute. The authors gratefully acknowledge the technical assistance provided by the staff of the EMF (Dr. P. Eschbach). APT research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Keywords

  • Duplex stainless steel (DSS)
  • G-phase
  • Transmission electron microscopy (TEM)

Fingerprint

Dive into the research topics of 'Measurement of G-phase volume fraction and number density in duplex stainless steels using transmission electron microscopy'. Together they form a unique fingerprint.

Cite this