STP287: Mechanical Properties of High-Strength 301 Stainless Steel Sheet at 70, −320, and −423 F in the Base Metal and Welded Joint Configuration

    Watson, James F.
    Convair-Astronautics, San Diego, Calif.

    Christian, J. L.
    Convair-Astronautics, San Diego, Calif.

    Pages: 14    Published: Jan 1961


    Abstract

    The ultimate tensile strength, elongation, and notched to unnotched tensile ratio of several tempers of high-strength 301 stainless steel sheet were determined at 70, −320, and −423 F. Specimens examined included smooth base metal, notched base metal (Kt = 6.3), and heliarc butt welds. The notched specimens were included in this study for the purpose of measuring notch sensitivity, which was taken as a criterion of sensitivity toward crack initiation and crack propagation. Microstructural studies and X-ray diffraction analyses were also conducted to study the mechanism of deformation at cryogenic temperatures. Tensile strengths and elongations of the base metal and welded joint specimens were generally observed to increase between room temperature and −320 F, and then to decrease between −320 and −423 F. The notched to unnotched tensile ratio remained close to 1.0 at −320 F, and then dropped to about 0.92 at −423 F. Extra-full-hard 301 stainless steel (cold rolled 60 per cent) exhibited tensile strengths of 230,000, 313,000, and 330,000 psi at 70, −320, and −423 F, respectively. The corresponding elongations were 5 per cent, 20 per cent, and 15 per cent. The notched to unnotched tensile ratio went from 1.0 at 70 F to 0.99 at −320 F, to 0.92 at −423 F. Specially rolled 301 steel cold worked 70 per cent to 300,000 psi at 70 F exhibited the same general type of behavior. Heliarc butt welds were observed to increase from 120,000 psi at 70 F to 278,000 psi at −320 F, and then to decrease to 255,000 psi at −423 F. The major factor contributing to the observed effects was shown to be the austenite-to-martensite reaction which is known to be favored by both low temperature and high tensile stress.


    Paper ID: STP46981S

    Committee/Subcommittee: E28.10

    DOI: 10.1520/STP46981S


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