Application of J-Integral to High-Temperature Crack Propagation: Part I—Creep Crack Propagation

1979 ◽  
Vol 101 (2) ◽  
pp. 154-161 ◽  
Author(s):  
Shuji Taira ◽  
Ryuichi Ohtani ◽  
Takayuki Kitamura
Keyword(s):  
Stainless Steel ◽  
Crack Propagation ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
304 Stainless Steel ◽  
J Integral ◽  
Creep Crack ◽  
Controlling Parameter ◽  
Testing Environments ◽  
Type 304

Crack propagation tests in creep were carried out on 0.16 percent carbon steel at 400 and 500°C in air and at 400°C in vacuum, on Type 316 stainless steel at 600 and 650°C in air, and on Type 304 stainless steel at 650°C in air and vacuum. As a nonlinear fracture mechanics approach, the applicability of the creep J-integral for a controlling parameter of the crack propagation rate was investigated using a few types of specimens subjected to constant tensile loads. A good correlation was obtained between crack propagation rate and creep J-integral. Crack propagation rate was nearly proportional to the creep J-integral, and the relationship was almost independent on the width of plate specimens, the test temperatures, the testing environments, and the fracture mode. The creep crack propagation rate in round notched bar specimens was a little smaller than that in the center notched plate specimens at the same magnitude of the creep J-integral.

Application of J-Integral to High-Temperature Crack Propagation: Part II—Fatigue Crack Propagation

1979 ◽  
Vol 101 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Shuji Taira ◽  
Ryuichi Ohtani ◽  
Tomio Komatsu
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Large Scale ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Integral Approach ◽  
Fatigue Crack Propagation Rate ◽  
J Integral ◽  
Creep Crack

On the basis of the successful results of our previous study on a J-integral approach to the creep crack propagation of steels, the applicability of the creep J-integral to the time dependent fatigue crack propagation in creep range was studied. A satisfactory correlation was obtained between crack propagation rate and creep J-integral, and the same correlation was found in creep crack propagation under constant load as well as two-step loading. It was also found that the cycle dependent fatigue crack propagation rate could be successfully correlated by the cyclic J-integral. The high crack propagation rate in large scale yielding fatigue may be in agreement with the straight line extrapolation on log-log plots of the linear elastic fatigue crack propagation rate versus cyclic J-integral data.

Stress corrosion property of 304 stainless steel and Q345 steel laser-MAG hybrid welded joints

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040057
Author(s):  
Hang Lv ◽  
Guoqing Gou ◽  
Zhenghong Fu ◽  
Wei Gao
Keyword(s):  
Stainless Steel ◽  
Crack Propagation ◽  
Stress Corrosion ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Corrosion Property ◽  
304 Stainless Steel ◽  
Propagation Path ◽  
Crack Propagation Path ◽  
Immersion Testing

The stress corrosion cracking (SCC) property of laser-MAG hybrid welded 304 stainless steel and Q345 steel was evaluated through cycle-immersion testing in 3.5 wt.% NaCl solution. The average SCC crack propagation rate of different zones under different initial stress intensity factors was calculated, and the SCC fracture and crack propagation path were observed. The microstructure and mechanical properties of the weld joint have also been examined. The result indicates that the fusion zone (FZ) is extremely prone to SCC. The average SCC crack propagation rate in FZ is [Formula: see text] mm/h, while no obvious SCC was found in the base metal (BM) and heat-affected zone (HAZ). The steel BM and HAZ may also suffer SCC, but not as fast as in FZ. Grooves caused by SCC were found on the fracture surface with a large amount of corrosion products accumulated close to the interface between the pre-crack section and SCC section. Crystallized-sugar-shaped pattern was found on the SCC zone of FZ. Crack jumping, deflection and crack closure occurred in the crack propagation path. Martensite on the FZ was considered to be the major reason that the FZ has a higher SCC propagation rate.

Applicability of Fracture Mechanics Parameters to Crack Propagation Under Creep Condition

1977 ◽  
Vol 99 (4) ◽  
pp. 298-305 ◽  
Author(s):  
R. Koterazawa ◽  
T. Mori
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Thin Plate ◽  
High Stress ◽  
Creep Condition ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Critical Examination ◽  
J Integral ◽  
Creep Crack

A critical examination was made of the applicability of fracture mechanics parameters to crack propagation under creep condition with 304 stainless steels for a variety of specimen geometries at relatively high stress levels. The creep crack propagation rate could not be described in terms of elastic stress intensity factor but it could be in terms of net section stress for all dimensions of thin plate specimen. The net section stress, however, could not explain the difference between crack propagation rates of thin plate specimens and those of notched round bar specimens. This difference could be ascribed to the plastic constraint around the crack tip. Applicability of the modified J-integral to creep crack propagation was also examined and the results showed that this parameter was better for predicting the creep crack propagation rate at a high stress level. In the case of speicmens of similar geometries, the net section stress could be used in place of the modified J-integral provided that crack propagation rate was divided by the characteristic length of the specimen.

FATIGUE CRACK GROWTH BEHAVIOR OF STAINLESS STEEL COATED WITH TiN FILM

2012 ◽  
Vol 06 ◽  
pp. 282-287
Author(s):  
SATOSHI FUKUI ◽  
DAISUKE YONEKURA ◽  
RI-ICHI MURAKAMI
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Crack Growth Behavior ◽  
Tin Film

In our previous study, we examined the influence of the fatigue properties of the stainless steel coated with TiN film and clarified the influence of TiN coating and the surface roughness on the fatigue property. In this study, the four point bending fatigue crack growth tests were carried out for martensitic stainless steel coated with TiN film deposited by arc ion plating method in order to investigate the effect of surface finishing on the fatigue crack behavior for film coated material. The fatigue crack growth behavior was evaluated using the replica method. As a result, the crack propagation rate of mirror polished specimens were lower than that of rough surface specimens. The crack propagation rate was especially decreased for TiN coatings deposited on the mirror polished substrate. The surface roughness near the crack initiation site increased after fatigue test. It concludes that the surface roughness of substrate influences crack propagation rate and the deposition of TiN film affected influenced crack propagation rate and fatigue strength when the surface roughness of substrate is small enough.

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