Trends and Implications of Data on Notched-Bar Creep Rupture

1962 ◽  
Vol 84 (2) ◽  
pp. 207-213 ◽  
Author(s):  
H. R. Voorhees ◽  
J. W. Freeman ◽  
J. A. Herzog
Keyword(s):  
Air Force ◽  
Rupture Life ◽  
Creep Rupture ◽  
University Of Michigan ◽  
Notched Specimens ◽  
Test Conditions ◽  
Unnotched Specimen ◽  
The University ◽  
Quantitative Explanation ◽  
Rupture Behavior

Extended research on creep rupture of notched specimens, conducted at the University of Michigan under Air Force sponsorship, is analyzed along with recent publications of others. The combined results suggest that notch strengthening is general for all alloys studied under some test conditions and is not specific to individual materials or to a given ductility level. Quantitative explanation of notch rupture behavior in terms of unnotched-specimen properties is handicapped by present uncertainties in the basic factors controlling creep-rupture life under variable multiaxial stress.

Capped End, Thin-Wall Tube Creep-Rupture Behavior for Type 316 Stainless Steel

1963 ◽  
Vol 85 (1) ◽  
pp. 71-86 ◽  
Author(s):  
G. H. Rowe ◽  
J. R. Stewart ◽  
K. N. Burgess
Keyword(s):  
Biaxial Tension ◽  
Rupture Life ◽  
Creep Rupture ◽  
Uniaxial Tensile ◽  
Thin Wall ◽  
Rupture Ductility ◽  
Statistical Argument ◽  
Stress Ratios ◽  
Rupture Properties ◽  
Rupture Behavior

The creep-rupture behavior of 34 capped end, thin-wall tubular specimens was correlated with results for 54 uniaxial tensile specimens in tests at 1350 F, 1500 F, and 1650 F. Basic tests established isotropy in creep-rupture properties as well as metallurgical stability for the material used in the study. Significant correlations of creep rate, rupture life, and rupture ductility were established for the cases of stress ratios 1/0 and 2/1 in the biaxial tension quadrant. Data from tests at 1500 F were evaluated for a statistical argument. This same material was subsequently utilized in a high temperature structures research program to be reported separately.

Creep-Rupture Behavior of Six Candidate Stirling Engine Superalloys Tested in Air

1984 ◽  
Vol 106 (1) ◽  
pp. 50-58 ◽  
Author(s):  
S. Bhattacharyya
Keyword(s):  
Creep Rate ◽  
Minimum Creep Rate ◽  
Rupture Life ◽  
Stirling Engine ◽  
Creep Rupture ◽  
Similar Data ◽  
Alloy 800H ◽  
Different Temperatures ◽  
Cast Alloys ◽  
Rupture Behavior

The creep-rupture behavior of six candidate Stirling engine iron-base superalloys was determined in air. The alloys included four wrought alloys (A-286, Alloy 800H, N-155, and 19-9DL) and two cast alloys (CRM-6D and XF-818). The specimens were tested to rupture for times up to 3000 h at 650° to 925°C. Rupture life (tr), minimum creep rate (ε˙m), and time to 1 percent creep strain (t0.01), were statistically analyzed as a function of stress and temperature. Estimated stress levels at different temperatures to obtain 3500 h tr and t0.01 lives were determined. These data will be compared with similar data being obtained under 15 MPa hydrogen.

The Effect of Stress Concentrations on the Creep Rupture of Tension Panels

1975 ◽  
Vol 42 (3) ◽  
pp. 613-618 ◽  
Author(s):  
D. R. Hayhurst ◽  
C. J. Morrison ◽  
F. A. Leckie
Keyword(s):  
Steady State ◽  
High Temperatures ◽  
Lower Bounds ◽  
Plane Stress ◽  
Rupture Life ◽  
Creep Rupture ◽  
Stress Concentrations ◽  
Engineering Structures ◽  
Aluminum Plates ◽  
Rupture Behavior

The creep rupture behavior of metals at high temperatures is reviewed for constant homogeneous states of multiaxial stress. Currently used methods for estimating the creep rupture life of engineering structures are discussed. The rupture lives of plane stress tension plates containing discontinuities are predicted by the different methods. The estimates of life are compared with the results of experiments carried out on copper and aluminum plates. It is shown that the magnitudes of the elastic and steady-state stresses do not influence the rupture behavior of the tension plates examined. The redistribution of stress in the structures which occurs due to tertiary creep plays an important part in determining the rupture lives. A method of predicting lower bounds on the structural rupture lives is presented and shown to closely predict the results of experiments.

Microstructure Evolution and Creep Rupture Behavior of Modified 9Cr-1Mo Steel Welded Joint

2020 ◽  
Author(s):  
Facai Ren ◽  
Xiaoying Tang ◽  
Jinsha Xu ◽  
Jun Si ◽  
Yiwen Yuan
Keyword(s):  
Electron Microscope ◽  
Microstructure Evolution ◽  
Welded Joint ◽  
Rupture Life ◽  
Optical Microscope ◽  
Creep Rupture ◽  
Creep Tests ◽  
Uniaxial Creep ◽  
Before And After ◽  
Rupture Behavior

Abstract Microstructure evolution and creep rupture behavior of modified 9Cr-1Mo steel welded joint used for steam cooler in high pressure heater system were systematically studied in this paper. Creep tests were carried out using uniaxial creep specimens machined from the normalized and tempered plate at 818K and 838K with the stresses ranging from 150 to 225MPa. The curve of stress vs. rupture time was achieved to evaluate the creep rupture life of modified 9Cr-1Mo steel welded joint. The creep data were analyzed in terms of Norton’s power law, Monkman-Grant relation and modified Monkman-Grant relation. Microstructure before and after creep exposure were analyzed by optical microscope, scanning electron microscope and transmission electron microscope, to further explain the rupture mechanisms of modified 9Cr-1Mo steel welded joint.

Cumulative Damage in Creep-Rupture Tests of a Carbon Steel

1962 ◽  
Vol 84 (2) ◽  
pp. 239-242 ◽  
Author(s):  
P. N. Randall
Keyword(s):  
Carbon Steel ◽  
Creep Rate ◽  
Rupture Life ◽  
Transient Creep ◽  
Creep Rupture ◽  
Stress Conditions ◽  
Constant Stress ◽  
Test Conditions ◽  
Prolonged Service ◽  
Life Fraction

A life-fraction rule is often used to predict the rupture life of a piece of elevated-temperature equipment exposed to several temperature and stress conditions. It is based on the assumption that the fraction of rupture life used up in a specific time at one stress and temperature is independent of previous conditions and therefore can be estimated from tests in which exposure conditions were held constant. Test data are needed to substantiate the validity of this rule. The results of 23 constant-stress creep-rupture tests on an ASTM A201A carbon steel have shown this rule to be valid when all of the test conditions caused appreciable creep strain. Even so, it may not be valid for prolonged service above 1100 F followed by service at lower temperatures. Creep rates are reasonably predictable for constant-stress conditions when only temperature is changed. The transient creep rate accompanying a change in stress continues long enough to make creep-rate predictions unreliable. Periodic shutdowns during tests at constant stress and constant temperature have little effect on either rupture life or creep rate.

Creep-Rupture Behavior of Unnotched and Notched Nickel-Base Alloys in Air and in Vacuum

1965 ◽  
Vol 87 (2) ◽  
pp. 344-350 ◽  
Author(s):  
P. Shahinian
Keyword(s):  
Heat Treatment ◽  
Low Temperatures ◽  
Rupture Life ◽  
High Strength ◽  
Creep Rupture ◽  
Atmosphere Effect ◽  
Nickel Base ◽  
Test Atmosphere ◽  
Rupture Properties ◽  
Rupture Behavior

The influence of test atmosphere on creep-rupture properties was determined for plain and notched bars of nickel, Nichrome V, Udimet 500, and Inconel X. The rupture life of nickel and of Nichrome V was shorter in air than in vacuum at relatively low temperatures, but at high temperatures it was longer in air. While both types of specimen geometry were generally affected alike by atmosphere, a larger atmosphere effect was observed for notched bars of the two materials in the air-strengthened region. The Udimet 500 and the high-strength Inconel X alloys at 1500 deg F were slightly stronger in vacuum than in air. However, the Inconel X with a modified heat-treatment displayed a reversal in the atmosphere effect. It was observed that all the materials generally develop intergranular cracks more readily in air than in vacuum.

Novae in the Magellanic Clouds

1979 ◽  
Vol 46 ◽  
pp. 96-101
Author(s):  
J.A. Graham
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
University Of Michigan ◽  
The Past ◽  
Spectroscopic Information ◽  
Objective Prism ◽  
The University ◽  
Small Cloud ◽  
Low Dispersion

During the past several years, a systematic search for novae in the Magellanic Clouds has been carried out at Cerro Tololo Inter-American Observatory. The Curtis Schmidt telescope, on loan to CTIO from the University of Michigan is used to obtain plates every two weeks during the observing season. An objective prism is used on the telescope. This provides additional low-dispersion spectroscopic information when a nova is discovered. The plates cover an area of 5°x5°. One plate is sufficient to cover the Small Magellanic Cloud and four are taken of the Large Magellanic Cloud with an overlap so that the central bar is included on each plate. The methods used in the search have been described by Graham and Araya (1971). In the CTIO survey, 8 novae have been discovered in the Large Cloud but none in the Small Cloud. The survey was not carried out in 1974 or 1976. During 1974, one nova was discovered in the Small Cloud by MacConnell and Sanduleak (1974).

Sign in / Sign up

Export Citation Format

Share Document