Abstract
The coaxing effect has been recognized as a phenomenon that enhances the fatigue resistance associated with work hardening and strain-age hardening. To uncover the intrinsic factors that affect the degree of coaxing effect, rotating bending fatigue tests including a process of stepwise stress increases every 107 cycles were carried out at ambient temperature in interstitial free steel and binary Fe-C ferritic alloys. The effects of the work hardening capacity, aging time, stress amplitude increment, and carbon concentration were examined in this simple alloy system. The work hardening capacity was changed by controlling carbon state in a Fe-0.017C (wt%) steel. However, the degree of coaxing effect did not show a significant correlation with work hardening capacity. For the effect of aging time, a fatigue test at a high stress amplitude was interrupted, aged for 2 weeks, and subsequently restarted. Although this process is sufficient to induce strain-age hardening in terms of aging time and plastic strain, a fatigue life of the aged steel was not comparable to that with the coaxing effect. Moreover, an increase in stress increment for each step deteriorated a degree of coaxing effect. It was concluded that the effect of work hardening is minor, and the other factors affecting strain-age hardening must be optimized simultaneously to show a coaxing effect. In addition, the degree of coaxing effect of smooth steel specimens was predominantly controlled by the intergranular fatigue crack initiation behavior. Consequently, a considerable amount of solute carbon and an alternate process for the stress amplitude increment and aging time are required for strain-age hardening that suppresses intergranular fatigue crack initiation.
| Original language | English |
|---|---|
| Pages (from-to) | 358-364 |
| Number of pages | 7 |
| Journal | isij international |
| Volume | 57 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Jan 1 2017 |
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All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry
Cite this
Intrinsic factors that trigger the coaxing effect in binary Fe-C ferritic alloys with a focus on strain aging. / Koyama, Motomichi; Ren, Bohong; Yoshimura, Nobuyuki; Sakurada, Eisaku; Ushioda, Kohsaku; Noguchi, Hiroshi.
In: isij international, Vol. 57, No. 2, 01.01.2017, p. 358-364.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Intrinsic factors that trigger the coaxing effect in binary Fe-C ferritic alloys with a focus on strain aging
AU - Koyama, Motomichi
AU - Ren, Bohong
AU - Yoshimura, Nobuyuki
AU - Sakurada, Eisaku
AU - Ushioda, Kohsaku
AU - Noguchi, Hiroshi
PY - 2017/1/1
Y1 - 2017/1/1
N2 - The coaxing effect has been recognized as a phenomenon that enhances the fatigue resistance associated with work hardening and strain-age hardening. To uncover the intrinsic factors that affect the degree of coaxing effect, rotating bending fatigue tests including a process of stepwise stress increases every 107 cycles were carried out at ambient temperature in interstitial free steel and binary Fe-C ferritic alloys. The effects of the work hardening capacity, aging time, stress amplitude increment, and carbon concentration were examined in this simple alloy system. The work hardening capacity was changed by controlling carbon state in a Fe-0.017C (wt%) steel. However, the degree of coaxing effect did not show a significant correlation with work hardening capacity. For the effect of aging time, a fatigue test at a high stress amplitude was interrupted, aged for 2 weeks, and subsequently restarted. Although this process is sufficient to induce strain-age hardening in terms of aging time and plastic strain, a fatigue life of the aged steel was not comparable to that with the coaxing effect. Moreover, an increase in stress increment for each step deteriorated a degree of coaxing effect. It was concluded that the effect of work hardening is minor, and the other factors affecting strain-age hardening must be optimized simultaneously to show a coaxing effect. In addition, the degree of coaxing effect of smooth steel specimens was predominantly controlled by the intergranular fatigue crack initiation behavior. Consequently, a considerable amount of solute carbon and an alternate process for the stress amplitude increment and aging time are required for strain-age hardening that suppresses intergranular fatigue crack initiation.
AB - The coaxing effect has been recognized as a phenomenon that enhances the fatigue resistance associated with work hardening and strain-age hardening. To uncover the intrinsic factors that affect the degree of coaxing effect, rotating bending fatigue tests including a process of stepwise stress increases every 107 cycles were carried out at ambient temperature in interstitial free steel and binary Fe-C ferritic alloys. The effects of the work hardening capacity, aging time, stress amplitude increment, and carbon concentration were examined in this simple alloy system. The work hardening capacity was changed by controlling carbon state in a Fe-0.017C (wt%) steel. However, the degree of coaxing effect did not show a significant correlation with work hardening capacity. For the effect of aging time, a fatigue test at a high stress amplitude was interrupted, aged for 2 weeks, and subsequently restarted. Although this process is sufficient to induce strain-age hardening in terms of aging time and plastic strain, a fatigue life of the aged steel was not comparable to that with the coaxing effect. Moreover, an increase in stress increment for each step deteriorated a degree of coaxing effect. It was concluded that the effect of work hardening is minor, and the other factors affecting strain-age hardening must be optimized simultaneously to show a coaxing effect. In addition, the degree of coaxing effect of smooth steel specimens was predominantly controlled by the intergranular fatigue crack initiation behavior. Consequently, a considerable amount of solute carbon and an alternate process for the stress amplitude increment and aging time are required for strain-age hardening that suppresses intergranular fatigue crack initiation.
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U2 - 10.2355/isijinternational.ISIJINT-2016-513
DO - 10.2355/isijinternational.ISIJINT-2016-513
M3 - Article
AN - SCOPUS:85013976664
VL - 57
SP - 358
EP - 364
JO - ISIJ International
JF - ISIJ International
SN - 0915-1559
IS - 2
ER -