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Title: Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar weld metals. Part 1 -- Nucleation and growth

Abstract

A fundamental investigation of fusion boundary microstructure evolution in dissimilar-metal welds (DMWs) between ferritic base metals and a face-centered-cubic (FCC) filler metal was conducted. The objective of the work presented here was to characterize the nature and character of the elevated-temperature fusion boundary to determine the nucleation and growth characteristics of DMWs. Type 409 ferritic stainless steel and 1080 pearlitic steel were utilized as base metal substrates, and Monel (70Ni-30Cu) was used as the filler metal. The Type 409 base metal provided a fully ferritic or body-centered-cubic (BCC) substrate at elevated temperatures and exhibited no on-cooling phase transformations to mask or disguise the original character of the fusion boundary. The 1080 pearlitic steel was selected because it is austenitic at the solidus temperature, providing an austenite substrate at the fusion boundary. The weld microstructure generated with each of the base metals in combination with Monel was fully austenitic. In the Type 409/Monel system, there was no evidence of epitaxial nucleation and growth as normally observed in homogeneous weld metal combinations. The fusion boundary in this system exhibited random grain boundary misorientations between the heat-affected zone (HAZ) and weld metal grains. In the 1080/Monel system, evidence of normal epitaxial growth wasmore » observed at the fusion boundary, where solidification and HAZ grain boundaries converged. The fusion boundary morphologies are a result of the crystal structure present along the fusion boundary during the initial stages of solidification. Based on the results of this investigation, a model for heterogeneous nucleation along the fusion boundary is proposed when the base and weld metals exhibit ferritic (BCC) and FCC crystal structures, respectively.« less

Authors:
; ;
Publication Date:
Research Org.:
Ohio State Univ., Columbus, OH (US)
OSTI Identifier:
20000597
Resource Type:
Journal Article
Journal Name:
Welding Journal (Miami)
Additional Journal Information:
Journal Volume: 78; Journal Issue: 10; Other Information: PBD: Oct 1999; Journal ID: ISSN 0043-2296
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; WELDED JOINTS; HEAT AFFECTED ZONE; MICROSTRUCTURE; STAINLESS STEELS; FILLER METALS; STEELS; NICKEL BASE ALLOYS

Citation Formats

Nelson, T W, Lippold, J C, and Mills, M J. Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar weld metals. Part 1 -- Nucleation and growth. United States: N. p., 1999. Web.
Nelson, T W, Lippold, J C, & Mills, M J. Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar weld metals. Part 1 -- Nucleation and growth. United States.
Nelson, T W, Lippold, J C, and Mills, M J. 1999. "Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar weld metals. Part 1 -- Nucleation and growth". United States.
@article{osti_20000597,
title = {Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar weld metals. Part 1 -- Nucleation and growth},
author = {Nelson, T W and Lippold, J C and Mills, M J},
abstractNote = {A fundamental investigation of fusion boundary microstructure evolution in dissimilar-metal welds (DMWs) between ferritic base metals and a face-centered-cubic (FCC) filler metal was conducted. The objective of the work presented here was to characterize the nature and character of the elevated-temperature fusion boundary to determine the nucleation and growth characteristics of DMWs. Type 409 ferritic stainless steel and 1080 pearlitic steel were utilized as base metal substrates, and Monel (70Ni-30Cu) was used as the filler metal. The Type 409 base metal provided a fully ferritic or body-centered-cubic (BCC) substrate at elevated temperatures and exhibited no on-cooling phase transformations to mask or disguise the original character of the fusion boundary. The 1080 pearlitic steel was selected because it is austenitic at the solidus temperature, providing an austenite substrate at the fusion boundary. The weld microstructure generated with each of the base metals in combination with Monel was fully austenitic. In the Type 409/Monel system, there was no evidence of epitaxial nucleation and growth as normally observed in homogeneous weld metal combinations. The fusion boundary in this system exhibited random grain boundary misorientations between the heat-affected zone (HAZ) and weld metal grains. In the 1080/Monel system, evidence of normal epitaxial growth was observed at the fusion boundary, where solidification and HAZ grain boundaries converged. The fusion boundary morphologies are a result of the crystal structure present along the fusion boundary during the initial stages of solidification. Based on the results of this investigation, a model for heterogeneous nucleation along the fusion boundary is proposed when the base and weld metals exhibit ferritic (BCC) and FCC crystal structures, respectively.},
doi = {},
url = {https://www.osti.gov/biblio/20000597}, journal = {Welding Journal (Miami)},
issn = {0043-2296},
number = 10,
volume = 78,
place = {United States},
year = {Fri Oct 01 00:00:00 EDT 1999},
month = {Fri Oct 01 00:00:00 EDT 1999}
}