Volume Fractions of Proeutectoid Ferrite/Pearlite and Their Dependence on Prior Austenite Grain Size in Hypoeutectoid Fe-Mn-C Alloys
Volume Fractions of Proeutectoid Ferrite/Pearlite and Their Dependence on Prior Austenite Grain Size in Hypoeutectoid Fe-Mn-C Alloys
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亚共析 Fe-Mn-C 合金中先共析铁素体/珠光体的体积分数及其对原奥氏体晶粒尺寸的依赖性
DOI：
10.1007/s11661-013-1885-6
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发表时间：
2013-07
影响因子：
2.8
通讯作者：
T. Furuhara
中科院分区：
文献类型：
--
作者：
Z.Q. Liu;G. Miyamoto;Z.G. Yang;T. Furuhara
一般认为，亚共析钢中珠光体转变开始于先共析铁素体形成后未转变奥氏体中平均碳浓度达到Acmline时。为了在实验上测试该概念，对于在848 K至898 K（575 °C至625 °C）的温度范围内等温转变的Fe-2 Mn-0.3C合金，测量了先共析铁素体/珠光体的体积分数和转变成珠光体的奥氏体中的碳含量。结果表明，即使未转变奥氏体中的平均碳含量远低于Acmline，也能形成片状珠光体。这种奇特的观察可能是由于碳的二维扩散，即，平行于和垂直于奥氏体/珠光体界面，这使得层状珠光体通过向其生长前沿供应碳原子而连续生长。这导致先共析铁素体相对于珠光体的分数远低于杠杆规则预测的分数。随着原奥氏体晶粒尺寸的减小，先共析铁素体相对于珠光体的分数增加，但先共析铁素体的厚度在所研究的晶粒尺寸范围内是恒定的。这是由于存在一个临界α/γ界面速度，只有低于该速度时，珠光体（实际上是珠光体）才能在迁移的α/γ界面上形核。Fe-1 Mn-0.33C和Fe-2 Mn-0.3C合金中珠光体形成的上限温度正好在PLE/NPLE和PE Ae 1温度之间。
It has been generally believed that pearlite transformation in hypoeutectoid steels starts when the average carbon concentration in untransformed austenite reaches the Acmline after the formation of proeutectoid ferrite. To test this concept experimentally, volume fractions of proeutectoid ferrite/pearlite and carbon contents in the austenite being transformed into pearlite were measured for the Fe-2Mn-0.3C alloy isothermally transformed in the temperature range 848 K to 898 K (575 °C to 625 °C). It was found that lamellar pearlite can form even when the average carbon content in untransformed austenite is much lower than the Acmline. This peculiar observation is probably due to the two-dimensional diffusion of carbon,i.e.,parallel to and normal to the austenite/pearlite interface, which enables lamellar cementite to grow continuously by supplying carbon atoms to its growth front. This results in proeutectoid ferrite fractions with respect to pearlite being much lower than those predicted by the lever rule. With decreasing prior austenite grain size, proeutectoid ferrite fractions with respect to pearlite were found to increase, but the thickness of proeutectoid ferrite was constant within the range of grain size investigated. This is due to the existence of the criticalα/γinterface velocity only below which pearlite (actually cementite) can be nucleated at the migratingα/γinterface. Furthermore, the upper limit temperatures for pearlite formation in the Fe-1Mn-0.33C and Fe-2Mn-0.3C alloys were found to be well between the PLE/NPLE and PE Ae1temperatures.
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影响因子：
6
作者：
M. Hillert;L. Höglund
通讯作者：
M. Hillert;L. Höglund
影响因子：
1.8
作者：
Seok Jae Lee;Young Kook Lee
通讯作者：
Seok Jae Lee;Young Kook Lee
DOI：
10.1146/annurev.ms.03.080173.001551
发表时间：
1973-08
期刊：
Annual Review of Materials Science
影响因子：
--
作者：
G. Meyrick;G. W. Powell
通讯作者：
G. Meyrick;G. W. Powell
DOI：
10.1007/bf02646386
发表时间：
1978-01-01
期刊：
METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
影响因子：
--
作者：
AARONSON, HI;PLICHTA, MR;RUSSELL, KC
通讯作者：
RUSSELL, KC
影响因子：
1.8
作者：
G. H. Zhang;M. Enomoto
通讯作者：
G. H. Zhang;M. Enomoto