Fracture toughness of partially welded joints of SUS316 stainless steel at 4 K by large bend tests

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · IEEE Transactions on Magnetics

DOI:https://doi.org/10.1109/20.511492· OSTI ID:367655

Nishimura, A; Tobler, R L; Tamura, H; Imagawa, S; Mito, T; Yamamoto, J; Motojima, O ^[1]; Takahashi, H; Suzuki, S ^[2]

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1. National Inst. for Fusion Science, Toki, Gifu (Japan)
2. Hitachi, Ltd., Ibaraki (Japan)

Austenitic stainless steels in relatively thick sections are specified in support structure designs for huge superconducting magnets in fusion energy machines such as the Large Helical Device (LHD). In the LHD under construction at the National Institute for Fusion Science (NIFS) in Japan, partial welding of SUS 316 stainless steel is employed to fabricate the 100-mm thick coil can and coil support structures. Partial welding lowers the heat input and reduces residual deformation after welding. The main disadvantage is that a sizable crack-like defect remains embedded in the unwelded portion of the primary structural component. Here, SUS 316 stainless steel bars were partially welded and tested in 3-point bending to evaluate the effect of natural cracks on fusion zone toughness at 4 K. The specimens had a cross-section 87.5 mm {times} 175 mm and were fractured in liquid helium using a 10 MN cryogenic mechanical testing machine. In two tests, unstable fracture occurred at maximum load and at critical stress intensity factors K{sub max} = 227 and 228 MPa{radical}m. Results indicate a high resistance to fracture initiation but no stable tearing. Therefore, no resistance to crack propagation may exist in a fusion zone at a weld root under cryogenic temperature.

• OSTI ID: 367655
• Report Number(s): CONF-950691--
• Journal Information: IEEE Transactions on Magnetics, Journal Name: IEEE Transactions on Magnetics Journal Issue: 4Pt1 Vol. 32; ISSN IEMGAQ; ISSN 0018-9464
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
EXPERIMENTAL DATA
FRACTURE PROPERTIES
MECHANICAL TESTS
STAINLESS STEEL-316
SUPERCONDUCTING MAGNETS
SUPPORTS
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTOR MATERIALS
WELDED JOINTS