Room Temperature Creep and its Effect on Fatigue Crack Growth in a X70 Steel with Various Microstructures

2007 ◽  
pp. 138-141
Author(s):  
De Fu Nie ◽  
Jie Zhao
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Room Temperature ◽  
Temperature Creep ◽  
Room Temperature Creep

Room Temperature Creep and its Effect on Fatigue Crack Growth in a X70 Steel with Various Microstructures

2007 ◽  
Vol 353-358 ◽  
pp. 138-141 ◽  
Author(s):  
De Fu Nie ◽  
Jie Zhao
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Room Temperature ◽  
Pipeline Steel ◽  
Threshold Region ◽  
Single Wave ◽  
Temperature Creep ◽  
Crack Tips ◽  
Room Temperature Creep

Fatigue crack growth (FCG) tests have been performed in an X70 steel with various microstructures (respectively in the as-received and the normalized condition). The effect of room temperature creep (RTC) on FCG behavior has been investigated by comparing with single wave overloads (SWOL). The as-received X70 pipeline steel has high FCG rate at the near-threshold region. While at the Paris region, FCG rate seems insensitive to the microstructure. In both conditions, time-dependent deformation is observed at crack tips (i.e., RTC), which increases with increasing stress-intensity-factor. And this deformation has a high value in the normalized state, under identical testing conditions. Both RTC and SWOL can bring subsequent fatigue crack growth a very short initial acceleration before deceleration, whereas the former induces more serious deceleration and retardation, which attributes to more significant crack closures.

Room Temperature Creep and Its Influence on Fatigue Crack Growth in a 304 Stainless Steel

2005 ◽  
Vol 297-300 ◽  
pp. 1083-1088 ◽  
Author(s):  
Jie Zhao ◽  
Tao Mo ◽  
Weixing Chen ◽  
Fu Gang Wang
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Room Temperature ◽  
304 Stainless Steel ◽  
Propagation Mode ◽  
Temperature Creep ◽  
Room Temperature Creep

The current paper investigated the phenomena of room temperature creep at the crack tip and its influence on fatigue crack growth behavior of a 304 stainless steel. From the experiments, a time-dependent deformation is obviously observed under various stress intensity factors. The deformation depends on stress intensity factor as well as load history. Both acceleration and retardation of fatigue crack growth are found after room temperature creep, which rest on load patterns. A distinct marking line was seen on the fracture surface following the holding period. It is proposed that the crack propagation mode changed after the hold time.

Fatigue Crack Growth in SA508-CL2 Steel in a High Temperature, High Purity Water Environment

1974 ◽  
Vol 96 (4) ◽  
pp. 255-260 ◽  
Author(s):  
T. L. Gerber ◽  
J. D. Heald ◽  
E. Kiss
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
High Purity ◽  
Room Temperature ◽  
Water Environment ◽  
Cyclic Frequency ◽  
Asme Code ◽  
Temperature Rate

Fatigue crack growth tests were conducted with 1 in. (25.4 mm) plate specimens of SA508-CL2 steel in room temperature air, 550 deg F (288 deg C) air and in a 550 deg F (288 deg C), high purity, water environment. Zero-tension load controlled tests were run at cyclic frequencies as low as 0.037 CPM. Results show that growth rates in the simulated Boiling Water Reactor (BWR) water environment are 4 to 8 times faster than growth rates observed in 550 deg F (288 deg C) air and these rates are 8 to 15 times faster than the room temperature rate. In the BWR water environment, lowering the cyclic frequency from 0.37 CPM to 0.037 CPM caused only a slight increase in the fatigue crack growth rate. All growth rates measured in these tests were below the upper bound design curve presented in Section XI of the ASME Code.

Fatigue Crack Growth in Co and Ni Base Directionally Solidified Eutectic Composites

1981 ◽  
Vol 12 ◽  
Author(s):  
C. Hoffmann ◽  
P. Bhowal ◽  
A. J. Mcevily
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Room Temperature ◽  
Interlamellar Spacing ◽  
Crack Growth Behavior ◽  
Directionally Solidified ◽  
Intensity Factors ◽  
Nickel Base ◽  
Cobalt Base

AbstractA study of fatigue crack growth behavior in four directionally solidified eutectic composites has been carried out in air at room temperature and at 870°C (1600 °F). The alloys investigated included two cobalt-base alloys, CoTaC and CoTaC+Cr, and two nickel base alloys, γ′-Mo and γ/γ′-δ. Fatigue crack growth was studied in directions parallel and perpendicular to the solidification direction. It was found that the addition of chromium to the CoTaC alloy strengthened the interface and promoted trans-fiber crack growth. In addition, the effect of interlamellar spacing on the rate of fatigue crack growth was examined for the γ/γ′-δ alloy. A reduction in interlamellar spacing reduced the crack growth rate. The growth rates are related to the corresponding stress intensity factors and are discussed in the light of prior investigations reported in the literature.

Constant and Variable Amplitude Fatigue Behavior of Five Cast Steels at Room Temperature and −45°C

1984 ◽  
Vol 106 (1) ◽  
pp. 25-37 ◽  
Author(s):  
R. I. Stephens ◽  
J. H. Chung ◽  
A. Fatemi ◽  
H. W. Lee ◽  
S. G. Lee ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Growth Behavior ◽  
Constant Amplitude ◽  
Variable Amplitude ◽  
Cast Steels ◽  
Variable Amplitude Fatigue

A comprehensive fatigue program was undertaken at room temperature and −45°C (−50°F) for five representative carbon or low alloy cast steels. Constant amplitude low and high cycle axial fatigue behavior, cyclic stress-strain behavior, constant-amplitude fatigue-crack-growth behavior and variable-amplitude fatigue-crack-initiation and -growth behavior were determined. The fatigue resistance at low temperature was usually equal to or better than at room temperature except for one material under variable amplitude fatigue crack growth conditions. SEM analysis revealed similar fatigue crack growth mechanisms at both room and low temperature, even though some tests were well below the NDT temperature. Most fatigue resistance for the five cast steels was consistent with that for wrought steels. Fatigue test procedures generally developed with wrought steels were completely satisfactory for these cast steels.

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