【作者】 邹菲菲；

【导师】 关小军；

【作者基本信息】 山东大学 ， 材料加工工程， 2007， 硕士

【摘要】 09CuPTiRE钢是我国独有的Cu-P-Ti-RE系列的耐大气腐蚀钢，广泛用于火车车体用材。近年来，随着铁路运输的飞速发展以及向青藏高原等气候恶劣地带的延伸，对09CuPTiRE钢的性能提出了更高的要求。由于热变形过程中，动态再结晶的发生程度对最终的组织性能有着重要的影响。因此，本文进行的09CuPTiRE钢在热变形过程中动态再结晶与工艺参数相关性的研究，不仅进一步充实了材料动态再结晶模拟的理论和技术，而且对于企业在实际生产中优化工艺参数、提高产品质量和降低成本都具有重要的指导意义。本文采用了热模拟实验、有限元分析技术和动态再结晶模型相结合的方法，引入热模拟实验的真应力—真应变曲线作为有限元模拟时的部分材料属性，考虑热变形过程中摩擦、传热、动态再结晶等因素的综合影响，得到更真实的变形分布，并结合所建的动态再结晶模型及其应用程序，对09CuPTiRE钢在热变形过程中的动态再结晶现象进行了模拟研究。从而得到了不同的压下制度、温度制度以及变形速率对09CuPTiRE钢动态再结晶的影响规律及其形成机理。首先，基于09CuPTiRE钢的热模拟实验和动态再结晶的相关理论，提出了基于真应力—真应变曲线和唯象JMA方程的动态再结晶模型；然后，在有限元软件DEFORM中模拟热变形过程；最后，基于已建立的动态再结晶数学模型和所编制的应用程序，系统地模拟了该钢热压缩和热轧期间的动态再结晶行为，实现了动态再结晶体积百分数分布的可视化，并进行了相关的分析研究。总结研究得到的具体结论如下：（1）在热压缩和热轧过程中，坯料内部都存在着变形不均匀的现象，并且模拟得到的动态再结晶体积百分数分布与变形分布基本一致。（2）动态再结晶一般始于大变形区，随着变形量的增加，逐渐向周边区域延伸，而且体积百分数也随之增大。（3）在变形量和变形速率一定的条件下，升高变形温度可以降低动态再结晶发生的临界条件，从而使发生再结晶以及完全再结晶的区域增大，显著地促进了动态再结晶的充分发生。（4）在变形量和变形温度一定的条件下，增大变形速率会阻碍动态再结晶发生，引起完全动态再结晶区域减小，软化程度减弱。（5）对于热轧而言，在轧制温度为1100℃、变形速率为10s^-1的条件下，相对压下量增加到0.45时，轧件整个截面几乎都进入完全再结晶状态；在相对压下量为0.5、变形速率为10s^-1的条件下，轧制温度升高到960℃时，整个截面也恰好进入完全再结晶状态；在总变形量为0.5、轧制温度为1100℃的条件下，当变形速率达到20s^-1时，距离轧辊出口50mm的轧件横截面仅发生了部分动态再结晶，不存在完全动态再结晶区域。（6）热轧过程中，轧件不同纵向位置处的动态再结晶发生程度是不同的。轧件前端再结晶发生最不充分，中部区域最好，后端稍差。更多还原

【Abstract】 09CuPTiRE steel is a Cu-P-Ti-RE series weather-resistant steel which is unique in the world. It is widely used for manufacturing the train carriages. In recent years, domestic railway transport develops quickly. With the railways extending to some areas of tough weather conditions, such as QingZang tableland, higher requirements for 09CuPTiRE steel properties are put forward. As we all know, the final microstructure and properties are affected by dynamic recrystallization during the hot deformation obviously. Consequently, the co-relationship between dynamic recrystallization and process parameters of 09CuPTiRE steel has been studied in this paper. The research not only enriches the theory and technology of dynamic recrystallization but also optimizes the process parameters, improves the product quality and cuts down the cost.By integrating the thermal simulating experiment with FEM simulation, dynamic recrystallization of 09CuPTiRE steel is studied. The true stress-strain curves are introduced as a part of material properties. Considering the effects of friction, heat exchange and dynamic recrystallization, the truer deformation distribution is achieved. Then with the dynamic recrystallization model and programs, the simulating results are acquired. The results mainly indicate how the deformation, strain-rate and temperature act on the dynamic recrystallization of 09CuPTiRE steel.Firstly, based on the thermal simulating experiment of 09CuPTiRE steel and relative theories, the model of dynamic recrystallization is established. Secondly, DEFORM is used to simulate hot deforming. Thirdly, program to realize the distribution of dynamic recrystallization volume fraction visible.According to the research, some conclusions are obtained as follows: （1） There is a kind of inhomogenous deformation. Distribution of dynamic recrystallization volume fraction agrees well with the distribution of deformation. （2） The dynamic recrystallization takes place at large deforming area firstly. With the increasing of deformation, dynamic recrystallization extends to the other areas and the volume fraction enhances. （3） When the deformation and strain-rate are changeless, high temperature can reduce the critical condition of dynamic recrystallization. Then the areas of partial and complete dynamic recrystallization become larger and dynamic recrystallization is promoted obviously. （4） When the deformation and temperature are invariable, high strain-rate baffles dynamic recrystallization. So it results in the reduction of complete dynamic recrystallizing area. （5） As for hot rolling, when rolling temperature is 1100°C and strain-rate is 10s^-1, the relative deformation that increases to 0.45 can make the whole section of workpiece at the state of complete dynamic recrystallization. When the relative deformation is 0.5 and strain-rate is 10s^-1, rolling temperature that increases to 960°C can also make the dynamic recrystallization take place completely. When the total deformation is 0.5, rolling temperature is 1100°C and the strain-rate increases to 20s^-1, the section that is 50mm from the exit can only keep the state of partial dynamic recrystallization and the complete dynamic recrystallization disappears. （6） During the hot rolling, dynamic recrystallization is different in the different longitudinal position of workpiece. At the front part, dynamic recrystallization happens inadequately. At the middle part, dynamic recrystallization takes place completely. At the back part, dynamic recrystallization almost takes place entirely.更多还原