TY - JOUR
T1 - Effect of grain size on the yield stress of cold worked iron
AU - Tanaka, Yuki
AU - Takaki, Setsuo
AU - Tsuchiyama, Toshihiro
AU - Uemori, Ryuji
N1 - Funding Information:
The 0.15%C steel used in this study was produced in the Japanese national project supported by NEDO (PROTEUS Project). The samples and data of strain-stress curves were provided by Nippon Steel & Sumitomo Metal Co. Besides, this study was supported by JSPS KAKENHI Grant Number JP15H05768.
Publisher Copyright:
© 2018 ISIJ
PY - 2018/10
Y1 - 2018/10
N2 - Effect of ferrite grain size on dislocation strengthening was investigated in low carbon steels (0.006%C-0.15%C) with various grain sizes from 1 to 100 m. In specimens with slight deformation, dislocation density increases in proportion to the inverse of ferrite grain size. In the dislocation density range below 2×1014/m2, dislocation density increases linearly against deformation strain but it tends to level off due to the dynamic recovery of dislocations when dislocation density has exceeded it. On the other hand, tensile tests revealed that yield stress follows the Hall-Petch relation for as-annealed specimens but follows the Bailey-Hirsch relation for cold rolled specimens. This means that flow stress depends on only the dislocation density regardless of grain size. As a result, it was concluded that the introduction of dislocations has been promoted with decreasing ferrite grain size and this results in the increase of flow stress in the uniform deformation region.
AB - Effect of ferrite grain size on dislocation strengthening was investigated in low carbon steels (0.006%C-0.15%C) with various grain sizes from 1 to 100 m. In specimens with slight deformation, dislocation density increases in proportion to the inverse of ferrite grain size. In the dislocation density range below 2×1014/m2, dislocation density increases linearly against deformation strain but it tends to level off due to the dynamic recovery of dislocations when dislocation density has exceeded it. On the other hand, tensile tests revealed that yield stress follows the Hall-Petch relation for as-annealed specimens but follows the Bailey-Hirsch relation for cold rolled specimens. This means that flow stress depends on only the dislocation density regardless of grain size. As a result, it was concluded that the introduction of dislocations has been promoted with decreasing ferrite grain size and this results in the increase of flow stress in the uniform deformation region.
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U2 - 10.2355/isijinternational.ISIJINT-2018-371
DO - 10.2355/isijinternational.ISIJINT-2018-371
M3 - Article
AN - SCOPUS:85055182621
VL - 58
SP - 1927
EP - 1933
JO - Transactions of the Iron and Steel Institute of Japan
JF - Transactions of the Iron and Steel Institute of Japan
SN - 0915-1559
IS - 10
ER -