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

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

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

Internet: An Overview of Key Technology Policy Issues Affecting Its Use and Growth

This report gives an overview of key technology policy issues of internet affecting its use and growth

Internet: An Overview of Key Technology Policy Issues Affecting Its Use and Growth

This report gives an overview of key technology policy issues of the internet affecting its use and growth

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

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

Radiation effects on BCC metals and alloys. Final report, March 1, 1970 to August 31, 1980

To contribute to more meaningful and self-consistent deformation and/or strengthening models, use was made of quantitative transmission electron microscopy to obtain the number density and size distribution of the various defect states in the irradiated material. With this information, the influence of defects on dislocation mobility and deformation modes was determined. In addition, by means of high temperature anneals for different time intervals, the original defect states was significantly changed so that the above dislocation-defect interaction models may be tested under many different conditions. Combinations of time at temperature and appied stress has been shown to be extremely important in the dislocation channeling phenomenon, a circumstance that is closely associated with irradiation induced embrittlement. Detailed resistivity measurements, a technique for determining defect thermal stability and recovery kinetics, was used to establish critical test temperatures

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

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