Fabrication and Evaluation of Weldments for Alloy 709 Commercial Heat Plates (FY 2019)

Zhili Feng, Yanli Wang, Tao Dai, Doug Kyle

Research output: Book/ReportCommissioned report

Abstract

Alloy 709 is an attractive candidate construction material for the Sodium Fast Reactor (SFR). As part of the Alloy 709 Intermediate Term Test Program, this work covers the development of the technical basis for weld fabrication and weld qualification of Alloy 709. The phase of research reported herein focused on the issue of weld solidification cracking recently experienced in some experimental heats of Alloy 709 with relatively high phosphorous levels. The computational simulation results revealed that that phosphorous has the most important impact on solidification behavior. Phosphorous is expected to significantly increase the susceptibility of weld solidification cracking of Alloy 709. A strategy to successfully weld Alloy 709 having wide range of chemistries without weld solidification cracking is developed to support ASME code qualification. The strategy includes use of low phosphorous level weld wire to weld Alloy 709 base metal having relatively high phosphorous. The welding experiment and subsequent weld qualification testing per ASME Section IX, conducted this reporting period, confirmed that a commercial heat Alloy 709 with 140wppm phosphorous can be successfully welded using a low phosphorous (20wppm) weld wire using the gas tungsten arc welding process and welding input levels typically used by industry. On the other hand, micro cracks are formed when the phosphorous level in the weld wire increases to 140wppm, which requires additional R&D to develop appropriate welding techniques to produce code qualified welds.
Original languageEnglish
Place of PublicationUnited States
DOIs
StatePublished - 2019

Keywords

  • 36 MATERIALS SCIENCE

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