Fatigue-Crack-Growth Behavior of Two Pipeline Steels

Journal Article · Mon Oct 17 00:00:00 EDT 2016 · Advanced Engineering Materials

DOI:https://doi.org/10.1002/adem.201600340· OSTI ID:1366379

Chen, Bilin ^[1]; Wang, Gongyao ^[1]; Chen, Shuying ^[1]; Muralidharan, Govindarajan ^[2]; Stalheim, Doug ^[3]; Sun, An-Cheng ^[4]; Huang, E-Wen ^[5]; Liaw, Peter K. ^[1]

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1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. DGS Metallurgical Solutions, Inc., Vancouver, WA (United States)
4. Yuan Ze Univ., Chung-Li (Taiwan). Dept. of Chemical Engineering and Materials Science
5. National Chiao Tung Univ., Hsinchu (Taiwan). Dept. of Materials Science and Engineering; Industrial Technology Research Inst., Hsinchu (Taiwan). Material and Chemical Research Lab.

This paper focuses on studying the fatigue-crack-growth behavior of two types of pipeline steels, and investigating their microstructural differences, which could influence the fatigue behavior. For fatigue experiments, compact-tension (CT) specimens are employed. These two kinds of base pipeline steels are Alloy B [Fe-0.05C-1.52Mn-0.12Si-0.092Nb, weight percent (wt.%)] and Alloy C [(Fe- 0.04C-1.61Mn-0.14Si-0.096Nb, wt.%)]. They have been tested at various frequencies (10 Hz, 1 Hz, and 0.1 Hz) and different R ratios (0.1 and 0.5, R = P_min./P_max. where P_min. is the minimum applied load, and P_max. is the maximum applied load) in air. The effects of frequencies and R ratios on crackpropagation behavior are compared. The microstructures of fracture surfaces are investigated, using both scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM). It is concluded that higher R ratios lead to faster crack-growth rates, while frequency does not have much influence on the fatigue-crack-growth rates. Moreover, Alloy B (Fe-0.05C-1.52Mn-0.12Si-0.092Nb, wt.%) tends to have better fatigue resistance than Alloy C (Fe-0.04C-1.61Mn-0.14Si-0.096Nb, wt.%) under various test conditions in air.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy (FE); Work for Others (WFO); Ministry of Science and Technology (MOST); US Department of Transportation; National Science Foundation (NSF)
• Grant/Contract Number: AC05-00OR22725; AC02-06CH11357; USDOTDTPH56-10-T-000001; FE0008855; FE0024054; FE0011194
• OSTI ID: 1366379
• Journal Information: Advanced Engineering Materials, Vol. 18, Issue 12; ISSN 1438-1656
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Pipeline steels
compact-tension (CT) specimens
fatigue-crack-growth rates