Modelling of kinetics and dilatometric behavior of non-isothermal pearlite-to-austenite transformation in an eutectoid steel
Modelling of kinetics and dilatometric behavior of non-isothermal pearlite-to-austenite transformation in an eutectoid steel
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DOI：
10.1016/s1359-6462(98)00146-8
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发表时间：
1998-08-11
影响因子：
6
通讯作者：
Bhadeshia, HKDH
中科院分区：
文献类型：
--
作者：
de Andres, CG;Caballero, FG;Bhadeshia, HKDH
奥氏体化是钢在热处理过程中不可避免的现象。尽管有这样的考虑，但与大量关于奥氏体分解的研究相比，迄今为止对奥氏体形成的研究关注较少。这是因为钢的性能基本上取决于奥氏体化后的转变过程。然而，初始奥氏体条件对最终显微组织及其机械性能的发展是重要的。在这个意义上，在以前的工作（1-3）中，研究了不同马氏体不锈钢和低碳微合金钢的连续加热转变图（CHT）。随着双相钢（4-7）的引入，在亚临界温度区的部分奥氏体化成为技术上的兴趣，并被广泛研究（8-11）。在这项工作中，作者强调了临界区退火前显微组织的重要性。Roosz等人(12)确定了初始显微组织对共析普碳钢等温处理过程中奥氏体形核速率和晶粒生长的影响。Avrami方程通常用于模拟等温条件下的转变（13）。然而，在本文中，我们提出了一个模型，在该模型中，该方程已成功地应用于模拟的珠光体到奥氏体的转变过程中连续加热的共析钢具有完全珠光体的初始显微组织。此外，由于热分析是一种经常用于研究钢中相变的技术，计算了长度的相对变化作为温度的函数，并分析了理论和实验结果之间的差异。
Austenitization is an inevitable occurrence during the heat treatment of steels. Despite this consideration, less attention has been paid so far to the study of the formation of austenite as compared with the vast amount of research on its decomposition. That is because the steel properties depend basically on the transformation processes following austenitization. However, the initial austenitic condition is important to the development of the final microstructure and its mechanical properties. In this sense, continuous heating transformation diagrams (CHT) of different martensitic stainless steels and low carbon microalloyed steels were studied in previous work (1–3). With the introduction of dual-phase steels (4–7), partial austenitization in the intercritical temperature region became of technological interest and was widely studied (8–11). In that work, the authors emphasise the importance of the microstructure immediately before intercritical annealing. Roosz et al.(12) determined the influence of the initial microstructure on the nucleation rate and grain growth of austenite during isothermal treatment of a eutectoid plain carbon steel.The Avrami equation is generally used to model transformations under isothermal conditions (13). However, in this paper we present a model in which this equation has been applied successfully in the modelling of the pearlite-to-austenite transformation during continuous heating in a eutectoid steel with a fully pearlitic initial microstructure. Moreover, since dilatometric analysis is a technique very often employed to study phase transformations in steels, calculations of relative change in length have been made as function of temperature, and the differences between theoretical and experimental results have been analysed.