78 research outputs found

    Correlation of Rupture Life, Creep Rate, and Microstructure for Type 304 Stainless Steel

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    The stress and temperature sensitivites of the rupture life and secondary creep rate were examined in detail for a single heat of type 304 stainless steel (9T2796). Assuming that the rupture life has a power law stress dependency, relatively small differences in the stress exponent were observed over a broad range of stress and temperature. In contrast, large changes were observed for equivalent parameter for secondary creep rate. As a result of these differences, the Monkman-Grant correlation was sensitive to stress and temperature below 650 C. Metallurgical studies based on light and transmission electron microscopy suggested that the temperature and stress sensitivities of secondary creep rate at temperatures below 650 C were related to features of the substructure not present at higher temperature. Specifically, the presence of a fine dislocation network stabilized by precipitates altered the stress and temperature sensitivities relative to what might be expected from high temperature studies

    Correlations Between Metallurgical Characterization Studies, Exploratory Mechanical Tests, and Continuum Mechanics Approaches to Constitutive Equations

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    Austenitic stainless steels, such as types 316 and 304, are widely used as pressure vessel materials in the temperature range of 425 to 650 C. Stainless steel specimens were tested to rupture at two different stress levels sigma and sigma 2 sigma 1 sigma 2) to establish the normal stain-time behavior. A subsequent test was performed in which the specimen was crept at the higher stress (sigma 1) to the beginning of the secondary stage of creep, presumed to be the strain/time conditions at which a steady state microstructure is developed, and then the stress was reduced to the lower level (sigma 2). The associated microstructure, and significance of this microstructure on the creep strain-hardening model for variable uniaxial loads were assesed and found to be consistent with the use of creep-recovery models at high stresses and temperatures and strain-hardening models at low stresses and tempertures

    Radiation effects on bcc metals and alloys. Progress report, January 1, 1973--December 31, 1973

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    Research programs directed toward evaluation of the effects of variables on the structure of bcc metals and alloys are described. Results of investigations are presented in sections on Mo, Nb, Nb -- Z r alloys. W, W-Re alloys, irradiation hardening, irradiation and fatigue interactions, and compressive creep of irradiated Mo. (JRD

    CORRELATION OF SUBSTRUCTURE WITH MECHANICAL PROPERTIES OF PLASTICALLY DEFORMED AISI 304 AND 316 STAINLESS STEEL. Progress Report, January 1, 1972--March 31, 1972.

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    Correlation of substructure with mechanical properties of plastically deformed AISI 304 and 316 stainless steel. Progress report, January 1--March 31, 1973

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    The recovery behavior of cold-worked AISI -316 stainless steel was studied using hot hardness. Hot hardness and substructure of AISI 304 stainless steel were correlated with tensile data, and transmission electron microscopy was carried out. The substructure of Incoloy 800 tensile tested at 800 to 1400 deg F was studied. (DLC

    CORRELATION OF SUBSTRUCTURE WITH MECHANICAL PROPERTIES OF PLASTICALLY DEFORMED AISI 304 AND 316 STAINLESS STEEL. Progress Report, October 1, 1971--December 31, 1971.

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    On the Effect of NaCl on Porosity in Elemental-Blend Powder-Metallurgy Ti-5AI-2.5Sn

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    The presence of small amounts (≤0.2 wt pct) of C1 influences the properties of Ti alloys produced by the elemental-blend method from Ti sponge manufactured by either the Hunter (Na reduction) or the Kroll (Mg reduction) technique
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