Effect of strain rate on deformation mechanism for ultrafine-grained interstitial-free steel

详细信息    查看全文

• 作者：Tetsuya Matsunaga ; ^{matsunaga@imr.tohoku.ac.jp} ; Shun Itoh ^{shun-itoh@imr.tohoku.ac.jp} ; Yuhki Satoh ^{ysatoh@imr.tohoku.ac.jp} ; Hiroaki Abe ^{abe.hiroaki@imr.tohoku.ac.jp}
• 关键词：Ultrafine grain ; Interstitial-free steel ; Strain-rate sensitivity ; Grain-boundary sliding ; Atomic force microscopy
• 刊名：Materials Science and Engineering: A
• 出版年：2013
• 出版时间：1 August, 2013
• 年：2013
• 卷：576
• 期：Complete
• 页码：267-271
• 全文大小：1634 K

文摘

Ultrafine-grained (UFG) interstitial-free steels with grain sizes of 0.39, 0.42, and 0.51 ¦Ìm were used to ascertain effects of the strain rate () on the primary deformation mechanism at room temperature. Tensile tests were performed to obtain the strain-rate sensitivity exponent of 0.2 % proof stress. The value was evaluated as 0.02 at high strain rates but as ?0.01 at low strain rates. The transition was observed at of 10^?3 s^?1 for each sample. Although the negative m value might result from strain aging, the influence of grain boundary sliding (GBS) increased remarkably at a low strain rate because it reached 76 % of plastic strain and became about six times as much as that at a high strain rate. Therefore, it is claimed that the dominant deformation mechanism was changed by the strain rate from dislocation motion to GBS with decreasing strain rate across ¡Ö10^?3 s^?1.