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| NF709奥氏体耐热钢的热变形行为 |
| Hot Deformation Behavior of NF709 Austenitic Heat-resistant Steel |
| Received:April 18, 2017 Revised:May 10, 2017 |
| DOI：10.3969/j.issn.1674-6457.2017.03.014 |
| 中文关键词: NF709奥氏体耐热钢 热变形 真应力-真应变曲线 本构方程 微观组织 |
| 英文关键词: NF709 austenitic heat-resistant steel hot deformation true stress-true strain curve constitutive equation microstructure |
| 基金项目:国家重点研发计划（2016YFB0300203）；国家能源应用技术研究及工程示范项目（NY201501） |
| Author Name | Affiliation | | BAO Han-sheng | Central Iron & Steel Research Institute, Institute of Special Steels, Beijing 100081, China | | WANG Jing-zhong | School of Metallurgy and Engineering, Xi’an University of Architecture and Technology, Xi’an, 710055, China | | LIU Zheng-dong | Central Iron & Steel Research Institute, Institute of Special Steels, Beijing 100081, China | | CHEN Zheng-zong | Central Iron & Steel Research Institute, Institute of Special Steels, Beijing 100081, China | | CHENG Jie-feng | Central Iron & Steel Research Institute, Institute of Special Steels, Beijing 100081, China |
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| 中文摘要: |
| 目的 获得NF709钢的热变形工艺参数。方法 利用Gleeble3800热模拟试验机，在变形温度为930~1230 ℃、应变速率为0.01~10 s-1、真应变为1.0的条件下，得到真应力-真应变曲线。依据流变应力曲线和相关热加工理论，建立材料的本构方程，分析试验钢的热变形特点。结果 该试验钢在试验条件下的热变形激活能为424 kJ/mol，建立了试验钢在变形条件下的本构方程，回归出了动态再结晶临界应力和Z参数之间的关系方程。根据动态组织分析和相应的热加工条件，建立了试验钢的动态组织状态图，可以用来预测不同变形条件下的动态组织。建立了应变速率、温度和峰值应力之间的关系方程。结论 在给定的变形温度或应变速率下，应变速率或变形温度对微观组织有显著影响。在1030~1230 ℃、应变速率为10 s-1的条件下，试验钢在变形量较小时容易失稳，随着应变量增加，流变失稳消失。 |
| 英文摘要: |
| The paper aims to obtain technological parameters on hot deformation of NF709. The Gleeble3800 thermal simulated test machine was adopted to obtain the true stress and true strain curve at temperature range of 930~1230 ℃, strain rates range of 0.01~10 s-1 and true strain of 1.0. The constitutive equation was established according to flow stress curve line and relevant hot processing theories to analyze thermal deformation features of the test steel. The hot deformation activation energy of the test steel was 424 kJ/mol. The constitutive equation of test steel was established. The relation equation between critical stress of dynamic recrystallization and parameter Z was regressed. Based on microstructure analysis and corresponding hot working conditions, the dynamic microstructure diagram of the test steel was established which can be used to predict the dynamic microstructure under different deformation conditions. The relation equation between strain rate, temperature and peak stress was established. The strain rate and deformation temperature have significant influences on microstructure at a given deformation temperature or strain rate. When deformation is carried out under the condition of 1030~1230 ℃ and 10 s-1, the test steel is easy to lose stability when strain is small, and the rheological instability disappears with the increase of strain. |
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