Effect of strain rate and temperature on the serration behavior of SA508-III RPV steel in the dynamic strain aging process
Xue Bai1,2,3. Su-jun Wu1,3 . Li-jun Wei1,3 . Shuai Luo1 . Xie Xie2 . Peter K. Liaw2
1 School of Materials Science and Engineering, Beihang University, Beijing 100191, China 2 Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996, USA 3 Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing 100191, China
Effect of strain rate and temperature on the serration behavior of SA508-III RPV steel in the dynamic strain aging process
Xue Bai1,2,3. Su-jun Wu1,3 . Li-jun Wei1,3 . Shuai Luo1 . Xie Xie2 . Peter K. Liaw2
1 School of Materials Science and Engineering, Beihang University, Beijing 100191, China 2 Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996, USA 3 Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing 100191, China
摘要 Dynamic strain aging (DSA) effect on SA508-III reactor pressure vessel (RPV) steel was investigated. The SA508-III RPV steel was subjected to tension tests at different strain rates (1.1 × 10-5 s-1 and 6.6 × 10-5 s-1) and different temperatures (500 and 550 °C) to evaluate the influence of strain rate and temperature on the serrated flow behavior, which is the repetitive and discontinuous yielding phenomenon on the stress–strain curves. The higher temperature leads to the higher density of precipitates, M23C6 carbides and needle-like Mo2C carbides. It was found that the samples under tension test of 6.6 × 10-5 s-1 and 500 °C possess superior mechanical properties and mainly show A-type serrations on the tension test curves. Then, the local regress method was used to filter the DSA curves, thus to show the real trend of the curves. It has been found that the less time of interaction between dislocations and precipitates under higher strain rates leads to a higher strength of the sample. The more tiny-stress drops on the 550 °C serration curve can be attributed to the hardening phase, M23C6 carbides and needle-like Mo2C carbides. The higher percentage of the small stress drops on the serration curves represents the higher mechanical strength.
Abstract：Dynamic strain aging (DSA) effect on SA508-III reactor pressure vessel (RPV) steel was investigated. The SA508-III RPV steel was subjected to tension tests at different strain rates (1.1 × 10-5 s-1 and 6.6 × 10-5 s-1) and different temperatures (500 and 550 °C) to evaluate the influence of strain rate and temperature on the serrated flow behavior, which is the repetitive and discontinuous yielding phenomenon on the stress–strain curves. The higher temperature leads to the higher density of precipitates, M23C6 carbides and needle-like Mo2C carbides. It was found that the samples under tension test of 6.6 × 10-5 s-1 and 500 °C possess superior mechanical properties and mainly show A-type serrations on the tension test curves. Then, the local regress method was used to filter the DSA curves, thus to show the real trend of the curves. It has been found that the less time of interaction between dislocations and precipitates under higher strain rates leads to a higher strength of the sample. The more tiny-stress drops on the 550 °C serration curve can be attributed to the hardening phase, M23C6 carbides and needle-like Mo2C carbides. The higher percentage of the small stress drops on the serration curves represents the higher mechanical strength.
XUE -Bai,WU Su-Jun,LIJUN -Wei, et al. Effect of strain rate and temperature on the serration behavior of SA508-III RPV steel in the dynamic strain aging process[J]. Journal of Iron and Steel Research International, 2018, 25(7): 767-752.
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2018, Vol. 25 
