TY - JOUR
T1 - ECCI Characterization of Dislocation Structures at a Non-propagating Fatigue Crack Tip
T2 - Toward Understanding the Effects of Mn-C and Cr-N Couples on Crack Growth Resistance
AU - Habib, Kishan
AU - Koyama, Motomichi
AU - Tsuchiyama, Toshihiro
AU - Noguchi, Hiroshi
N1 - Funding Information:
This study was financially supported by JSPS KAKENHI (JP16H06365).
Publisher Copyright:
© 2018, The Minerals, Metals & Materials Society and ASM International.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - We attempted to clarify the underlying mechanisms of the enhanced small-fatigue-crack resistance of Fe-Mn-C twinning-induced plasticity (TWIP) steel and high-nitrogen austenitic steel. To this end, we performed electron channeling contrast imaging near the tips of non-propagating fatigue cracks in Fe-18Cr-14Ni steel without a significant amount of interstitials, Fe-23Mn-0.5C TWIP steel, and Fe-25Cr-1N austenitic steel. The fatigue crack non-propagation limits of the TWIP steel and high-nitrogen steel were higher than that of the steel without a significant amount of interstitials; the higher limits of the TWIP steel and high-nitrogen steel are attributed to the Mn-C and Cr-N interactions, respectively. The enhanced small-fatigue-crack resistance of the Fe-23Mn-0.5C steel is attributed to local hardening at the crack tip caused by an increase in the dislocation density via dynamic strain aging. The enhanced dislocation planarity of the Fe-25Cr-1N steel, which is a result of the Cr-N interaction, is a significant factor that influences (i.e., increases) the crack resistance. The enhanced dislocation planarity results in dislocation pile-up stress at the crack tip, thereby preventing dislocation emission from the crack tip.
AB - We attempted to clarify the underlying mechanisms of the enhanced small-fatigue-crack resistance of Fe-Mn-C twinning-induced plasticity (TWIP) steel and high-nitrogen austenitic steel. To this end, we performed electron channeling contrast imaging near the tips of non-propagating fatigue cracks in Fe-18Cr-14Ni steel without a significant amount of interstitials, Fe-23Mn-0.5C TWIP steel, and Fe-25Cr-1N austenitic steel. The fatigue crack non-propagation limits of the TWIP steel and high-nitrogen steel were higher than that of the steel without a significant amount of interstitials; the higher limits of the TWIP steel and high-nitrogen steel are attributed to the Mn-C and Cr-N interactions, respectively. The enhanced small-fatigue-crack resistance of the Fe-23Mn-0.5C steel is attributed to local hardening at the crack tip caused by an increase in the dislocation density via dynamic strain aging. The enhanced dislocation planarity of the Fe-25Cr-1N steel, which is a result of the Cr-N interaction, is a significant factor that influences (i.e., increases) the crack resistance. The enhanced dislocation planarity results in dislocation pile-up stress at the crack tip, thereby preventing dislocation emission from the crack tip.
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U2 - 10.1007/s11661-018-4972-x
DO - 10.1007/s11661-018-4972-x
M3 - Article
AN - SCOPUS:85055945578
SN - 1073-5623
VL - 50
SP - 426
EP - 435
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
IS - 1
ER -