Effects of Gaseous Hydrogen on Fatigue Crack Growth Behavior of Low Carbon Steel

2009 ◽  
Author(s):  
Dongsun Lee ◽  
Hide-aki Nishikawa ◽  
Yasuji Oda ◽  
Hiroshi Noguchi
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Ductile Fracture ◽  
Crack Growth ◽  
Strain Range ◽  
Hydrogen Gas ◽  
Crack Growth Behavior ◽  
Low Carbon ◽  
Nitrogen Gas

In order to investigate the effects of hydrogen on the fatigue crack growth behavior of low carbon steel JIS S10C, bending fatigue tests were carried out using a specimen with a small blind artificial hole in a low pressure pure hydrogen gas atmosphere. The results show that the fatigue crack growth rate in hydrogen gas is higher than that in nitrogen gas, moreover, the degree of acceleration is greater in the high strain range. In fractography, intergranular facets mixed with ductile fracture and quasi-cleavage fracture with brittle striations appear in a hydrogen gas environment, while only ductile fracture mainly appears in nitrogen gas. In the low growth rate range, many intergranular facets are seen on the ductile fracture surface, and in the higher growth rate range, quasi-cleavage facets increase as the growth rate increases. The growth rate of a small crack in nitrogen gas can be expressed by dl/dN ∝ Δεpnl in the wide range of applied total strain range Δεt. The same type equation is also satisfied in hydrogen gas, but in the narrow range roughly from Δεt = 0.25% to Δεt = 0.37%. The fracture surface in this range shows only intergranular facets and a ductile morphology, but no quasi-cleavage fracture. Although the crack growth mechanism in hydrogen is different from that in nitrogen, observation of the mechanism of intergranular facet formation shows a similarity to the mechanism in nitrogen in which the slip-off mechanism of crack growth is valid. The formation of intergranular facets is also closely related to the slip behavior influenced by hydrogen. This means that there exists a high possibility for the application of the small crack growth law inhydrogen to not only S10C, but also to other carbon steels in which the intergranular facet appears.

Influence of Testing Frequency on Fatigue Crack Growth of 6061-T6 Aluminum Alloy in Hydrogen Gas Environment

2007 ◽  
Vol 353-358 ◽  
pp. 174-177 ◽  
Author(s):  
Akiyoshi Hagihara ◽  
Yasuji Oda ◽  
Hiroshi Noguchi
Keyword(s):  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Hydrogen Gas ◽  
Nitrogen Gas ◽  
Testing Frequency ◽  
Gas Environment

In order to investigate the effects of testing frequency on the fatigue crack growth rate of 6061-T6 aluminum alloy in hydrogen gas environment, fatigue crack growth tests were carried out on specimens with small artificial holes in 0.18 MPa hydrogen gas or in 0.18 MPa nitrogen gas. It takes long time to test at low testing frequency, so in this study an accelerated test method was proposed and fatigue tests were carried out using this method. The fatigue crack growth rate in hydrogen gas environment accelerates compared with in nitrogen gas environment. The crack growth rate at lower testing frequency tends to higher.

Fatigue Characteristics of Low Carbon Steel in Hydrogen Gas Environment

2007 ◽  
Vol 345-346 ◽  
pp. 1051-1054 ◽  
Author(s):  
Hiroshi Noguchi ◽  
Yasuji Oda
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Carbon Steel ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Low Carbon Steel ◽  
Hydrogen Gas ◽  
Low Carbon ◽  
Hydrogen Environment ◽  
Gas Environment

In order to investigate the effect of hydrogen environment on fatigue crack growth characteristics of a low carbon steel JIS S10C, fatigue crack growth tests were conducted in a low pressure hydrogen gas environment. Fatigue crack growth rate in hygrogen gas is higher than that in nitrogen gas. It seems that a crack in the range of low growth rate prefers to propagate along the grain boundaries under hydrogen environment while in the range of high growth across the grains accompanied by brittle striation patterns or river patterns. It is important to clarify how hydrogen affects the crack growth behavior of different stages of crack growth.

Effect of KIII on Fatigue Crack Growth Behavior

2010 ◽  
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Chikako Ohdama
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Tests ◽  
Crack Growth Behavior ◽  
Crack Growth Simulation ◽  
Slant Surface ◽  
Cracked Specimens

Mixed mode fatigue tests are conducted using surface cracked specimen. Slant surface cracked specimens are made where crack angle is 15°, 30°, 45° and 60°. It is shown that factory roof is made at deepest point of surface crack due to ΔKIII, and crack growth rate decreases by the factory roof. Fatigue crack growth is simulated using S-version FEM (Finite Element Method) using crack growth criteria. It is shown that conventional crack growth criteria are not available to predict fatigue crack growth with factory roof. In this study, modified criterion for the prediction of crack growth rate is proposed. By using this criterion, fatigue crack growth simulation is conducted, and results are compared with those of experiments and discussed.

Experiment and Modeling of Fatigue Crack Growth With Altering Loading Direction

2009 ◽  
Author(s):  
Wenfeng Tu ◽  
Xiaogui Wang ◽  
Zengliang Gao
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Growth Behavior ◽  
Cyclic Plasticity ◽  
Crack Growth Behavior ◽  
Loading Direction

The experiments of mixed Mode I-II fatigue crack growth with altering loading direction were conducted with compact specimens made of 16MnR steel. The specimens were tested under three loading steps. When the crack reached a certain length in the first step, the loading direction was switched to a certain angle. Finally, the loading direction was returned to the original orientation. The crack grow direction had a tendency perpendicular to the loading axis. Right after the loading direction was changed, the crack growth rate was retarded. A new approach developed was used to predict the crack growth behavior. The elastic-plastic stress analysis was performed using the finite element method with the implementation of a cyclic plasticity model. Based on the stress-strain response, fatigue damage near the crack tip was determined by a multi-axial fatigue criterion. Both the crack growth rate and cracking direction were obtained according to the maximum fatigue damage distribution on the critical material plane. The predictions for the crack growth behavior including the crack growth rate and crack growth path were in agreement with the experimental data.

Summary of an ASME/DOT Project on Measurements of Fatigue Crack Growth Rate of Pipeline Steels

2014 ◽  
Author(s):  
Andrew J. Slifka ◽  
Elizabeth S. Drexler ◽  
Robert L. Amaro ◽  
Damian S. Lauria ◽  
Louis E. Hayden ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Yield Strength ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Hydrogen Gas ◽  
Lessons Learned ◽  
Pipeline Steels

The National Institute of Standards and Technology has been testing pipeline steels for about 3 years to determine the fatigue crack growth rate in pressurized hydrogen gas; the project was sponsored by the Department of Transportation, and was conducted in close collaboration with ASME B31.12 Committee on Hydrogen Piping and Pipelines. Four steels were selected, two X52 and two X70 alloys. Other variables included hydrogen gas pressures of 5.5 MPa and 34 MPa, a load ratio, R, of 0.5, and cyclic loading frequencies of 1 Hz, 0.1 Hz, and a few tests at 0.01 Hz. Of particular interest to ASME and DOT was whether the X70 materials would exhibit higher fatigue crack growth rates than the X52 materials. API steels are designated based on yield strength and monotonic tensile tests have historically shown that loss of ductility correlates with increase in yield strength. The X70 materials performed on par with the X52 materials in fatigue. The test matrix, the overall set of data, implications for the future, and lessons learned during the 3-year extensive test program will be discussed.

Fatigue Crack Growth Rates of HPS 485W in China

2010 ◽  
Vol 452-453 ◽  
pp. 157-160
Author(s):  
Chun Sheng Wang ◽  
Lan Duan ◽  
Jing Yu Hu
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
High Fracture Toughness ◽  
Stress Intensity Factor Range ◽  
Low Carbon ◽  
High Fracture

This paper provides an introduction of existing fatigue and fracture behavior studies about high performance steel (HPS). This paper is emphasis on the crack propagation studies of HPS 485W, which is a new kind of structural weathered steel produced by Wuyang Steel Company using quenching and tempering (Q&T) in China. HPS has more advantages than traditional steel, such as high fracture toughness and cracking tolerance, high strength, low preheating weld or no preheating, recycle using and so on, so it can be used in sustainable bridge and building structures with low carbon releasing. To ensure the using safety and extend applying area of the new green civil material, the key material properties of HPS should be studied, such as fatigue crack growth rate. Fatigue crack growth rate characterizes the material resistance to stable crack extension under cyclic loading. A set of 5 compact specimens were made from 8mm and 14mm thick HPS 485W separately. Fatigue crack growth rate function of crack-tip stress-intensity factor range, da/dN versus ΔK, is proposed based on the test results, which shows HPS has high cracking tolerance ability.

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