STP668: Tensile and Fracture Behavior of a Nitrogen-Strengthened, Chromium-Nickel-Manganese Stainless Steel at Cryogenic Temperatures

    Tobler, RL
    Metallurgist and section chief, Institute for Basic Standards, National Bureau of Standards, Boulder, Colo.

    Reed, RP
    Metallurgist and section chief, Institute for Basic Standards, National Bureau of Standards, Boulder, Colo.

    Pages: 16    Published: Jan 1979


    Abstract

    J-integral fracture and conventional tensile properties are reported for an electroslag remelted Fe-21Cr-6Ni-9Mn austenitic stainless steel that contains 0.28 percent nitrogen as an interstitial strengthening element. Results at room (295 K), liquid-nitrogen (76 K), and liquid-helium (4 K) temperatures demonstrated that the yield strength and fracture toughness of this alloy are inversely related and strongly temperature dependent. Over the investigated temperature range, the yield strength tripled to 1.24 GPa (180 ksi) at 4 K. The fracture toughness, as measured using 3.8-cm-thick (1.5 in.) compact specimens, decreased considerably between 295 and 4 K. During plastic deformation at 295 K the alloy undergoes slight martensitic transformation, but at 76 and 4 K it transforms extensively to martensites. The amount of body-centered cubic (bcc) martensite formed during tension tests was measured as a function of elongation.

    Keywords:

    cryogenics, fracture, low-temperature tests, martensitic transformations, mechanical properties, stainless steel alloys, crack propagation


    Paper ID: STP35847S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP35847S


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