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Title: Co-dependent microstructural evolution pathways in metastable d-ferrite in cast austenitic stainless steels during thermal aging

Abstract

Cast austenitic stainless steels (CASS) are excellent alloys because they combine high corrosion resistance with high strength and toughness. However, they are susceptible to embrittlement upon long-term thermal aging at elevated temperatures. Thus, the microstructural evolution pathways during thermal aging need to be understood to predict and potentially prevent embrittlement. Atom probe tomography was used to identify and quantify the microstructural evolution pathways of the d-ferrite in different CASS alloys aged for up to 10,000 hours at temperatures between 290 °C and 400 °C. The four steels – CF8, CF8M, CF3, and CF3M – which vary by Mo and C concentration, each experienced spinodal decomposition of the d-ferrite, and precipitation of G-phase clusters and Cu clusters attached to the G-phase. There were large differences in the extent of these features due to their Mo and C concentration. Using radial distribution function analysis, the interactions of constituent elements was found to determine the evolution of these features, with Mo and C specifically influencing the movement of Cr, Ni, Si, Mn, and Cu atoms due to their relative miscibility with these elements. The results will help inform predictive models for the use of duplex stainless steels for extended operation at high temperatures.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]; ORCiD logo [1]
  1. BATTELLE (PACIFIC NW LAB)
  2. Oak Ridge National Laboratory
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1511267
Report Number(s):
PNNL-SA-135407
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 510
Country of Publication:
United States
Language:
English
Subject:
Duplex stainless steel, Aging, Spinodal decomposition, Precipitation kinetics, atom probe tomography (APT)

Citation Formats

Lach, Timothy G., Devaraj, Arun, Leonard, Keith J., and Byun, Thak Sang. Co-dependent microstructural evolution pathways in metastable d-ferrite in cast austenitic stainless steels during thermal aging. United States: N. p., 2018. Web. doi:10.1016/j.jnucmat.2018.08.038.
Lach, Timothy G., Devaraj, Arun, Leonard, Keith J., & Byun, Thak Sang. Co-dependent microstructural evolution pathways in metastable d-ferrite in cast austenitic stainless steels during thermal aging. United States. doi:10.1016/j.jnucmat.2018.08.038.
Lach, Timothy G., Devaraj, Arun, Leonard, Keith J., and Byun, Thak Sang. Mon . "Co-dependent microstructural evolution pathways in metastable d-ferrite in cast austenitic stainless steels during thermal aging". United States. doi:10.1016/j.jnucmat.2018.08.038.
@article{osti_1511267,
title = {Co-dependent microstructural evolution pathways in metastable d-ferrite in cast austenitic stainless steels during thermal aging},
author = {Lach, Timothy G. and Devaraj, Arun and Leonard, Keith J. and Byun, Thak Sang},
abstractNote = {Cast austenitic stainless steels (CASS) are excellent alloys because they combine high corrosion resistance with high strength and toughness. However, they are susceptible to embrittlement upon long-term thermal aging at elevated temperatures. Thus, the microstructural evolution pathways during thermal aging need to be understood to predict and potentially prevent embrittlement. Atom probe tomography was used to identify and quantify the microstructural evolution pathways of the d-ferrite in different CASS alloys aged for up to 10,000 hours at temperatures between 290 °C and 400 °C. The four steels – CF8, CF8M, CF3, and CF3M – which vary by Mo and C concentration, each experienced spinodal decomposition of the d-ferrite, and precipitation of G-phase clusters and Cu clusters attached to the G-phase. There were large differences in the extent of these features due to their Mo and C concentration. Using radial distribution function analysis, the interactions of constituent elements was found to determine the evolution of these features, with Mo and C specifically influencing the movement of Cr, Ni, Si, Mn, and Cu atoms due to their relative miscibility with these elements. The results will help inform predictive models for the use of duplex stainless steels for extended operation at high temperatures.},
doi = {10.1016/j.jnucmat.2018.08.038},
journal = {Journal of Nuclear Materials},
number = ,
volume = 510,
place = {United States},
year = {2018},
month = {11}
}