Effects of large amounts of hydrogen on the fatigue crack growth behavior of torsional prestrained carbon steel
The effects of large amounts of hydrogen on the fatigue crack growth properties of torsional prestrained ferritic–pearlitic low-carbon steel were investigated. Hydrogen-precharged specimens were produced by conducting cathodic charge to the virgin material and to torsional prestrained JIS-S10C and...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2016-01-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero35/numero_35_art_01.pdf |
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| Summary: | The effects of large amounts of hydrogen on the fatigue crack growth properties of torsional
prestrained ferritic–pearlitic low-carbon steel were investigated. Hydrogen-precharged specimens were
produced by conducting cathodic charge to the virgin material and to torsional prestrained JIS-S10C and JISS25C
steels (hereafter S10C and S25C steels). Rotating bending fatigue tests were conducted in air at room
temperature. Hydrogen content, CH, increased with torsional prestrain for both S10C and S25C steels; the CH of
the torsional prestrained S25C steel precharged with hydrogen was lower than that of S10C at the same
torsional prestrain. No clear difference between the maximum CH values of the torsional fractured S10C and
S25C hydrogen-precharged steel specimens. With respect to crack initiation, there was no obvious difference
between the uncharged and precharged specimens in spite of the large amount of CH induced by torsional
prestrain. The acceleration of fatigue crack growth by hydrogen was the main cause of the decreased fatigue life.
For the virgin material, hydrogen had no obvious effect on the fatigue crack growth rate. In contrast, for the
torsional prestrained materials, the acceleration ratios, {(da/dN)H/(da/dN)U}, increased with the torsional
prestrain and CH. However, {(da/dN)H/(da/dN)U} did not exceed the value of about 30, even when a large
amount of hydrogen was charged (10.0 ≤ CH ≤ 30.3 mass ppm). A hydrogen content threshold was found;
hydrogen content above this limit enhances the growth of the non-propagated crack, even for metals with lower
hardness (HV < 200). |
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| ISSN: | 1971-8993 1971-8993 |