Effect of intercritical deformation on microstructure and mechanical properties of a low-silicon aluminum-added hot-rolled directly quenched and partitioned steel
Effect of intercritical deformation on microstructure and mechanical properties of a low-silicon aluminum-added hot-rolled directly quenched and partitioned steel
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临界变形对低硅铝热轧直接淬火配分钢显微组织和力学性能的影响
DOI：
10.1016/j.msea.2016.01.040
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发表时间：
2016-02-22
期刊：
影响因子：
6.4
通讯作者：
Raabe, Dierk
中科院分区：
文献类型：
--
作者：
Tan, Xiao-Dong;Xu, Yun-Bo;Raabe, Dierk
在这里，我们采用热轧结合直接淬火和分配（HDQ&P）工艺与不同的轧制计划，以低C低硅铝添加钢。采用亚温轧制和热轧后空冷的方法在钢中引入铁素体。研究了临界变形对合金组织演变和力学性能的影响。系统地探讨了适度亚温变形对奥氏体稳定化的促进作用和TRIP效应的优化。结果表明，添加1.46wt%的Al能有效促进铁素体的形成。高于800 ℃的亚温变形可导致铁素体的显著双峰晶粒尺寸分布和一些含有亚晶粒的细长铁素体晶粒。奥氏体和铁素体的残余应变状态以及贝氏体转变的发生共同增加了残余奥氏体分数，这是由于其机械稳定性和从其周围相进入奥氏体的增强的碳分配。低于800 ℃的亚温变形可以显著增加铁素体分数并促进变形铁素体的再结晶。大部分铁素体的形成促进了未转变奥氏体中碳的富集，并延缓了配分过程中的贝氏体转变，最终促进了马氏体转变并降低了残余奥氏体分数。残余奥氏体有效的TRIP效应和贝氏体可能的应变分配共同改善了钢的加工硬化和成形性，并导致具有相对较高的抗拉强度（905 MPa）、低屈强比（0.60）和高总延伸率（25.2%）的优异机械性能。(C)© 2016 Elsevier B.V.版权所有。
Here, we applied hot-rolling in conjunction with direct quenching and partitioning (HDQ&P) processes with different rolling schedules to a low-C low-Si Al-added steel. Ferrite was introduced into the steel by intercritical rolling and air cooling after hot-rolling. The effect of intercritcal deformation on the microstructure evolution and mechanical properties was investigated. The promotion of austenite stabilization and the optimization of the TRIP effect due to a moderate degree of intercritical deformation were systematically explored. The results show that the addition of 1.46 wt% of Al can effectively promote ferrite formation. An intercritical deformation above 800 degrees C can result in a pronounced bimodal grain size distribution of ferrite and some elongated ferrite grains containing sub-grains. The residual strain states of both austenite and ferrite and the occurrence of bainite transformation jointly increase the retained austenite fraction due to its mechanical stabilization and the enhanced carbon partitioning into austenite from its surrounding phases. An intercritical deformation below 800 degrees C can profoundly increase the ferrite fraction and promote the recrystallization of deformed ferrite. The formation of this large fraction of ferrite enhances the carbon enrichment in the untransformed austenite and retards the bainite transformation during the partitioning process and finally enhances martensite transformation and decreases the retained austenite fraction. The efficient TRIP effect of retained austenite and the possible strain partitioning of bainite jointly improve the work hardening and formability of the steel and lead to the excellent mechanical properties with relatively high tensile strength (905 MPa), low yield ratio (0.60) and high total elongation (25.2%). (C) 2016 Elsevier B.V. All rights reserved.