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您的检索式：作者名="Nack J.Kim"
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| 1 | Effects of Processing Parameters on Microstructure and Properties of Ultra High Strength Linepipe Steel显示文摘To examine the effect of processing parameters on microstructural evolution and to obtain the excellent combination of strength and toughness,simulation of thermo-mechanical processing was conducted using the Gleeble machine.Trial production was then conducted under the conditions obtained by Gleeble tests.Based on the results of microstructure analysis and mechanical property evaluation,the relationship between microstructural features and mechanical properties was elucidated.The result shows that the volume fraction of constituted phases can be controlled through adjusting the cooling rate and finish cooling temperature in order to get different strength levels.As cooling rate increases,the volume fraction of upper bainite increases,which leads to the increase of strength.The upper shelf energy(USE) increases with increasing volume fraction of acicular ferrite in bainite base because of the small effective acicular ferrite grain size.Ductile-brittle transition temperature(DBTT) decreases with increasing acicular ferrite volume fraction.High reduction in the rough stage has great influence on grain refinement. | Xiaodan Wu Hakcheol Lee Young Min Kim Nack J.Kim | 2012 | Journal of Materials Science & Technology2012，28，10： | 4 |
| 2 | Effects of Cu addition on formability and surface delamination phenomenon in high-strength high-Mn steels显示文摘The formability of austenitic high-Mn steels is a critical issue in automotive applications under nonuniformly-deformed environments caused by dynamic strain aging.Among austenite stabilizing alloying elements in those steels,Cu has been known as an effective element to enhance tensile properties via controlling the stacking fault energy and stability of austenite.The effects of Cu addition on formability,however,have not been sufficiently reported yet.In this study,the Cu addition effects on formability and surface characteristics in the austenitic high-Mn TRIP steels were analyzed in consideration of inhomogeneous microstructures containing the segregation of Mn and Cu.To reveal determining factors,various mechanical parameters such as total elongation,post elongation,strain hardening rate,normal anisotropy,and planar anisotropy were correlated to the hole-expansion and cup-drawing test results.With respect to microstructural parameters,roles of(Mn,Cu)-segregation bands and resultant Cu-rich FCC precipitates on the formability and surface delamination were also discussed. | Min Chul Jo Jisung Yoo Min Cheol Jo Alireza Zargaran Seok Su Sohn Nack J.Kim Sunghak Lee | 2020 | Journal of Materials Science & Technology2020，36，8： | 0 |
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