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Microstructural features of dissimilar welds between 316LN austenitic stainless steel and alloy 800
Mopati Sireesha
Published in Elsevier Sequoia SA, Lausanne
2000
Volume: 292
   
Issue: 1
Pages: 74 - 82
Abstract
For joining type 316LN austenitic stainless steel to modified 9Cr-1Mo steel for power plant application, a trimetallic configuration using an insert piece (such as alloy 800) of intermediate thermal coefficient of expansion (CTE) has been sometimes suggested for bridging the wide gap in CTE between the two steels. Two joints are thus involved and this paper is concerned with the weld between 316LN and alloy 800. These welds were produced using three types of filler materials: austenitic stainless steels corresponding to 316, 16Cr-8Ni-2Mo, and the nickel-base Inconel 182. The weld fusion zones and the interfaces with the base materials were characterized in detail using light and transmission electron microscopy. The 316 and Inconel 182 weld metals solidified dendritically, while the 16-8-2 (16%Cr-8%Ni-2%Mo) weld metal showed a predominantly cellular substructure. The Inconel weld metal contained a large number of inclusions when deposited from flux-coated electrodes, but was relatively inclusion-free under inert gas-shielded welding. Long-term elevated-temperature aging of the weld metals resulted in embrittling sigma phase precipitation in the austenitic stainless steel weld metals, but the nickel-base welds showed no visible precipitation, demonstrating their superior metallurgical stability for high-temperature service.
About the journal
JournalData powered by TypesetMaterials Science and Engineering A
PublisherData powered by TypesetElsevier Sequoia SA, Lausanne
ISSN09215093
Open AccessNo
Concepts (15)
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    Austenitic transformations
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    Chromium alloys
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    DISSIMILAR METALS
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    Electrodes
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    Embrittlement
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    Inclusions
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    Interfaces (materials)
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    Metallographic microstructure
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    Nickel alloys
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    Solidification
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    Stainless steel
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    Thermal expansion
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    INCONEL ALLOY 182
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    THERMAL EXPANSION COEFFICIENT
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    Welds