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.

Time to Initiation of Tertiary Creep Property of Grade 91 Steels

2016 ◽  
Author(s):  
Kazuhiro Kimura ◽  
Kota Sawada
Keyword(s):  
Creep Rate ◽  
Minimum Creep Rate ◽  
Rupture Life ◽  
Creep Rupture ◽  
Tertiary Creep ◽  
Time To Initiation ◽  
Wide Range ◽  
Minimum Stress ◽  
Grade 91

Creep deformation property of Grade 91 steels was analyzed on more than 370 creep curves over a wide range of time to rupture from about 10 hours to beyond 100,000 hours, in order to evaluate time to 1% total strain, time to minimum creep rate and time to initiation of tertiary creep. Time to initiation of tertiary creep was assessed as a 0.2% offset with a slope of minimum creep rate. It is difficult to determine time to minimum creep rate precisely, which is a basis of 0.2% offset, however, it has been confirmed that time to initiation of tertiary creep is not sensitive to the time when the creep rate indicates minimum value. Life ratio of 1% total strain time against creep rupture time increases up to about 60% with increase of temperature and decrease of stress. Life ratio of time to initiation of tertiary creep also tends to increase with decrease in stress. However, change of it is in a range of 50 to 60% of creep rupture life over a wide range of creep rupture life from 10 hours to 100,000 hours, and it is not sensitive to creep test temperature. Over a range of temperatures from 500 to 600°C and up to about 200,000 hours, a temperature and time-dependent stress intensity limit, St is controlled by 67% of minimum stress to rupture. However, a difference between 67% of minimum stress to rupture and 80% of minimum stress to initiation of tertiary creep decreases with increases in temperature and time, and both values approach each other in the long-term beyond about 100,000 hours at 600°C. In the long-term beyond about 10,000 hours at 650°C, St is controlled by 80% of minimum stress to initiation of tertiary. The stable life fraction of time to initiation of tertiary creep establish a reliability of a temperature and time-dependent stress intensity limit value.

Long Term Creep Properties of a Die-Cast Mg-Al-Ca Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 163-166
Author(s):  
Yoshihiro Terada ◽  
Tatsuo Sato
Keyword(s):  
Creep Rate ◽  
Magnesium Alloys ◽  
Cast Alloy ◽  
Rupture Life ◽  
Testing Temperature ◽  
Creep Rupture ◽  
Die Cast ◽  
Cast Magnesium Alloys ◽  
Term Creep ◽  
Cast Magnesium

Creep rupture tests were performed for a die-cast Mg-Al-Ca alloy AX52 (X representing calcium) at 29 kinds of creep conditions in the temperature range between 423 and 498 K. The creep curve for the alloy is characterized by a minimum in the creep rate followed by an accelerating stage. The minimum creep rate (ε& m) and the creep rupture life (trup) follow the phenomenological Monkman-Grant relationship; trup = C0 /ε& m m. It is found for the AX52 die-cast alloy that the exponent m is unity and the constant C0 is 2.0 x 10-2, independent of creep testing temperature. The values of m and C0 are compared with those for another die-cast magnesium alloys. The value m=1 is generally detected for die-cast magnesium alloys. On the contrary, the value of C0 sensitively depends on alloy composition, which is reduced with increasing the concentration of alloying elements such as Al, Zn and Ca.

Very-Short-Time, Very-High-Temperature Creep Rupture of Type 347 Stainless Steel and Correlation of Data

1969 ◽  
Vol 91 (1) ◽  
pp. 32-38 ◽  
Author(s):  
C. D. Lundin ◽  
A. H. Aronson ◽  
L. A. Jackman ◽  
W. R. Clough
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Minimum Creep Rate ◽  
Creep Rupture ◽  
Aisi Type ◽  
Data Scatter ◽  
Long Time ◽  
Short Time ◽  
Very High ◽  
Rupture Behavior

Available equipment initially developed for welding research studies was used to investigate the creep-rupture behavior of AISI type 347 stainless steel in a very-high-temperature range from 62 to 86 percent of the solidus. Stress applications from 900 to 28,000 psi gave rupture times from a fraction of a second to several hundred seconds with thousandfold variations of minimum creep rate. Results could be presented by conventional means. Data scatter on a Monkman-Grant plot was typical. Correlation and extrapolation procedures developed by Larson-Miller, Manson-Haferd, Dorn, Korchynsky, and Conrad for conventional long-time results were found to be applicable, with preference being given to the Manson-Haferd procedures.

Creep Deformation Behavior and Microstructural Degradation During Creep of Pre-Strained 25Cr-20Ni-Nb-N Steel

2007 ◽  
Author(s):  
Nobuhiko Saito ◽  
Nobuyoshi Komai
Keyword(s):  
Creep Rate ◽  
Creep Deformation ◽  
Deformation Behavior ◽  
Minimum Creep Rate ◽  
Strengthening Mechanism ◽  
Creep Rupture ◽  
Microstructural Degradation ◽  
Solution Treated ◽  
Long Time ◽  
Strained Materials

The purpose of this study is to clarify the creep deformation behavior and microstructural degradation during creep of pre-strained 25Cr-20Ni-Nb-N steel (TP310HCbN), which has the highest creep strength among austenite stainless steels used for boiler tubes. The creep rupture strengths of the 20% pre-strained materials tested at 650°C under 210 MPa and 180 MPa were higher than those of solution-treated materials. However, the long time creep rupture strengths of the 20% pre-strained materials tested at 700°C and 750°C were lower than those of solution-treated materials. Thus, the creep strengths of the prestrained materials depend on test temperature and stress. Furthermore, the minimum creep rate of the 20% pre-strained materials and re-solution-treated materials tested at 650°C under 300MPa were 1.2 × 10−9 and 1.6 × 10−8 s−1, respectively. Thus, the minimum creep rate of the 20% pre-strained materials was lower than for re-solution-treated materials. The creep strengthening mechanism of the pre-strained materials at 650°C was considered to be that high-density dislocations were maintained until the late stage of creep. On the other hand, the creep rupture strengths of the 20% pre-strained materials were lower than those of solution-treated materials tested at over 700°C because of agglomeration and coarsening of precipitates and the recovery of dislocations.

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.

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.

Shortening the Long Creep Strength Evaluation Period with the Assistant of Stress Relaxation Behavior

2018 ◽  
Vol 774 ◽  
pp. 553-558
Author(s):  
Tie Shan Cao ◽  
Cong Qian Cheng ◽  
Jie Zhao
Keyword(s):  
Creep Rate ◽  
Stress Relaxation ◽  
Creep Strength ◽  
Rupture Life ◽  
Creep Rupture ◽  
Creep Data ◽  
Heat Resistant Steel ◽  
Evaluation Period ◽  
Short Period ◽  
Similar Deformation

P92 heat-resistant steel was used to demonstrate that creep rupture life evaluation period could be shorted by the assistant of the creep data from short-period stress relaxation test without reducing the prediction precision. Research showed that the minimum creep rate and the relaxation creep rate were exchangeable, and the stress exponent and the apparent activation energy analysis of the constant strain creep and the constant stress creep showed a similar deformation mechanism at the condition of T and . The creep rupture life predicted through the combination of these two kinds of creep data was closer to the real creep data than that evaluated by the traditional method based on the time to rupture only, and the precision of the evaluated creep strength increased at last 14.5 %.

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