The entering behavior of environmental gases into the plastic zone around fatigue crack tips in titanium

Masayuki Shimojo, R. Iguchi, T. H. Myeong, Y. Higo

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Fatigue crack growth tests were performed on titanium in vacuum, a nitrogen gas, inert gases (helium and argon), and air. Fracture surface morphologies were different from each other even if these environments were mild. Microcracks which were parallel to the striations were observed on the fracture surfaces, and the frequency of them increased with the environment becoming active (He < N 2 < Air). These results suggest that the environment has some effects on the deformation behavior in the plastic zone at the crack tip. The concentration of nitrogen in the plastic zone around a crack surface tested in nitrogen was analyzed using electron probe microanalysis (EPMA). The concentration of nitrogen in the plastic zone, especially in the cyclic plastic zone, increased significantly. The result indicates that nitrogen may be adsorbed on the fresh surfaces produced at the crack tip during loading and diffuse into the cyclic plastic zone with cyclic dislocation movement. Considering all the results, it can be thought that atoms of environmental gases including argon, as well as nitrogen, have some effects on the chemical composition of the cyclic plastic zone.

Original languageEnglish
Pages (from-to)1341-1346
Number of pages6
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume28
Issue number6
Publication statusPublished - 1997
Externally publishedYes

Fingerprint

crack tips
Titanium
Crack tips
Nitrogen
plastics
titanium
Gases
Plastics
nitrogen
gases
Argon
argon
Noble Gases
Helium
surface cracks
striation
microcracks
air
Electron probe microanalysis
Microcracks

ASJC Scopus subject areas

  • Materials Science(all)
  • Metals and Alloys

Cite this

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abstract = "Fatigue crack growth tests were performed on titanium in vacuum, a nitrogen gas, inert gases (helium and argon), and air. Fracture surface morphologies were different from each other even if these environments were mild. Microcracks which were parallel to the striations were observed on the fracture surfaces, and the frequency of them increased with the environment becoming active (He < N 2 < Air). These results suggest that the environment has some effects on the deformation behavior in the plastic zone at the crack tip. The concentration of nitrogen in the plastic zone around a crack surface tested in nitrogen was analyzed using electron probe microanalysis (EPMA). The concentration of nitrogen in the plastic zone, especially in the cyclic plastic zone, increased significantly. The result indicates that nitrogen may be adsorbed on the fresh surfaces produced at the crack tip during loading and diffuse into the cyclic plastic zone with cyclic dislocation movement. Considering all the results, it can be thought that atoms of environmental gases including argon, as well as nitrogen, have some effects on the chemical composition of the cyclic plastic zone.",
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T1 - The entering behavior of environmental gases into the plastic zone around fatigue crack tips in titanium

AU - Shimojo, Masayuki

AU - Iguchi, R.

AU - Myeong, T. H.

AU - Higo, Y.

PY - 1997

Y1 - 1997

N2 - Fatigue crack growth tests were performed on titanium in vacuum, a nitrogen gas, inert gases (helium and argon), and air. Fracture surface morphologies were different from each other even if these environments were mild. Microcracks which were parallel to the striations were observed on the fracture surfaces, and the frequency of them increased with the environment becoming active (He < N 2 < Air). These results suggest that the environment has some effects on the deformation behavior in the plastic zone at the crack tip. The concentration of nitrogen in the plastic zone around a crack surface tested in nitrogen was analyzed using electron probe microanalysis (EPMA). The concentration of nitrogen in the plastic zone, especially in the cyclic plastic zone, increased significantly. The result indicates that nitrogen may be adsorbed on the fresh surfaces produced at the crack tip during loading and diffuse into the cyclic plastic zone with cyclic dislocation movement. Considering all the results, it can be thought that atoms of environmental gases including argon, as well as nitrogen, have some effects on the chemical composition of the cyclic plastic zone.

AB - Fatigue crack growth tests were performed on titanium in vacuum, a nitrogen gas, inert gases (helium and argon), and air. Fracture surface morphologies were different from each other even if these environments were mild. Microcracks which were parallel to the striations were observed on the fracture surfaces, and the frequency of them increased with the environment becoming active (He < N 2 < Air). These results suggest that the environment has some effects on the deformation behavior in the plastic zone at the crack tip. The concentration of nitrogen in the plastic zone around a crack surface tested in nitrogen was analyzed using electron probe microanalysis (EPMA). The concentration of nitrogen in the plastic zone, especially in the cyclic plastic zone, increased significantly. The result indicates that nitrogen may be adsorbed on the fresh surfaces produced at the crack tip during loading and diffuse into the cyclic plastic zone with cyclic dislocation movement. Considering all the results, it can be thought that atoms of environmental gases including argon, as well as nitrogen, have some effects on the chemical composition of the cyclic plastic zone.

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