Softening mechanisms and microstructure evolution of 42CrMo steel during hot compressive deformation
Softening mechanisms and microstructure evolution of 42CrMo steel during hot compressive deformation
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DOI：
10.1016/j.jmrt.2023.02.141
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发表时间：
2023-03-04
影响因子：
6.4
通讯作者：
Yang, Congcong
中科院分区：
文献类型：
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作者：
Wang, Qingjuan;He, Zeen;Yang, Congcong
利用Gleeble-3500热模拟试验机对42 CrMo钢进行了不同条件下的热压缩试验。系统研究了不同变形条件下的组织演变和流动行为。结果表明，流变曲线在低应变速率和高温下出现明显的峰值，峰值应力随变形温度的降低和应变速率的增加而增大。由加工硬化曲线推导出了不同变形条件下的动态再结晶临界点。峰值应变（ep）与临界应变（ec）之间的关系满足ec 1/4 0.65ep。随着应变速率的降低和变形温度的升高，ec值降低。结合高温组织和临界应变，确定了不同变形条件下的软化机制。低温变形时，合金的软化机制为动态回复（DRV）和动态再结晶（DRX）相结合;高温变形时，合金的软化机制主要为动态再结晶（DRX），在低应变速率下，变形后的动态再结晶晶粒粗化。室温下的微观结构分析表明，在热压缩过程中引入的子结构可以影响相变。电子背散射衍射结果表明，动态再结晶不完全时，室温组织中的中取向角晶界比例较高，平均局部应变较大。不完全动态再结晶组织中较高的位错密度破坏了马氏体多级结构，而完全动态再结晶组织中则倾向于形成典型的马氏体多级结构。(c)2023作者。由Elsevier B. V.发布。这是CC BY-NC-ND许可证下的开放获取文章（http：//creativecommons.org/licenses/by-nc-nd/4.0/）。
Hot compression experiments were conducted on 42CrMo steel under different conditions using a Gleeble-3500 thermomechanical simulator. Systematic studies on the microstruc-ture evolution and flow behavior under different deformation conditions were conducted. The results demonstrate that the flow curves exhibit significant peaks at low strain rates and high temperatures, and that the peak stress increases with decreasing deformation temperature and increasing strain rate. The dynamic recrystallization (DRX) critical points under various deformation conditions were derived from the work-hardening curves. The relationship between the peak (ep) and critical (ec) strains satisfies ec1/4 0.65ep. The value of ec decreased as the strain rate decreased and deformation temperature increased. The softening mechanism under different deformation conditions was determined in conjunction with the high-temperature microstructure and critical strains. When deformed at low temperature, the softening mechanism was a combination of dynamic recovery (DRV) and DRX; when deformed at high temperature, the softening mechanism was mainly DRX, and at low strain rates, the deformed DRX grains coarsened. Analysis of the room-temperature microstructure revealed that the substructure introduced during hot compression can affect the phase transition. Electron backscatter diffraction results show that room-temperature microstructure have a higher proportion of medium orien-tation angle boundaries and greater average local strain when DRX is incomplete. The higher dislocation density in the tissue with incomplete DRX disrupts the martensitic multilevel structure, whereas with complete DRX, it tends to form a typical martensitic multilevel structure. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).