【作者】 王丽敏；

【导师】 周天瑞； 王丽娟；

【作者基本信息】 南昌大学 ， 材料加工工程， 2011， 硕士

【摘要】 先进高强度钢板在汽车制造领域的应用是有效地实现汽车轻量化和提高整车被动安全性的有效途征之一。热冲压成形是一种专门用于制造复杂形状的先进高强度钢零件的新技术,且零件的回弹很小。此技术的工艺过程是先将板料的温度升至再结晶温度以上某一温度值,然后将加热后的板料移至模具上,成形和淬火处理同时进行,得到了拥有高强度的零部件的成形工艺。此过程是一个涉及到了模具与板料的传热、成形以及板料微观组织的转变,故对工艺参数对板料的流变行为的影响规律进行探讨,对热冲压零件的成形过程进行分析,从而制定热冲压成形的工艺,对热冲压成形技术的理论和实际应用具有重要指导意义。本文以先进高强度硼钢板Mn22B5作为研究对象,采用了实验研究、理论分析以及数值模拟相结合的方法,在对高强度硼钢板热冲压成形工艺进行了分析的基础上,制定了物理热模拟实验方案,即板料处于完全奥氏体化后,再将板料的温度降至不同的温度,以不同的应变速率对板料进行等温单向拉伸实验,得到了在不同的条件下,材料的真实应力-应变曲线,并在此基础上对变形温度与变形速率对板料的流变行为的影响及规律性进行了分析。在实验结果的基础上,建立了高强度硼钢板的热冲压流变应力数学模型。以汽车防撞梁的典型特征件U形件作为研究对象,在分析了成形时的受力和高强度硼钢板热冲压成形的流变应力数学模型基础上,建立了与材料性能参数、工艺参数以及几何参数有关的热冲压U形件侧壁的最大应变解析模型。采用有限元数值模拟技术,对高强度硼钢板U形件的热冲压成形过程进行了数值模拟,在有限元软件ABAQUS上建立了热成形件的热冲压成形过程的模型。数值模拟主要对压边力和模具间隙在热冲压成形过程中的对成形的零件质量的影响进行了探讨。从数值模拟的结果来看,本文所建立的有限元模型在对模拟热冲压成形过程是很有效的。在压边力较大时,零件的回弹较小,有利于改善法兰与模具的接触作用,同时可以避免成形零件发生开裂现象。模具间隙对侧壁上的温度分布有较大的影响,模具间隙越大,成形件侧壁的温度就越高。更多还原

【Abstract】 Application of advanced high strength steel in the automotive manufacturing field is an effective vehicle to achieve light weight and improve vehicle passive safety.Hot stamping is a advanced new technology with specialized manufacture for complex shapes of high-strength steel components, and a very small back spring. Process of this technology is sheet of the temperature rose to a temperature above the recrystallization temperature, and then moved the heated sheet to the mold, forming and quenching, and get the parts with high strength. This process is related to the mold and the sheet metal heat transfer, sheet metal forming and microstructure change, so the process parameters on the rheological behavior of sheet discusses the impact of law, forming part of the hot stamping process of analysis, to develop hot stamping process. Hot stamping technology that will better applied to the actual production is great significance.In this paper, high-strength boron steel Mn22B5 advanced is the research object. Using the experimental research, theoretical analysis and numerical simulation method of combining, high-strength boron steel in the hot stamping process is analyzed based on the physical development of thermal simulation experiment Program, the sheet is fully austenitized, then the temperature dropped to different temperature, different strain rate on the isothermal sheet tensile test obtained the true stress-strain curves. Based on this curves, deformation temperature and strain rate on the rheological behavior of sheet metal and the regularity are analyzed. Based on the experimental results, flow stress model of high-strength boron steel in hot stamping is established.The high strength boron steel U shaped piece of hot stamping process was simulated by finite element numerical simulation. Based on explicit ABAQUS software environment, several key issues, such as sheet metal contact between the treatment and die, determination of material properties and mesh division of finite element software ABAQUS to establish the heat of hot forming parts forming process model.更多还原