【作者】 尹成凯；

【导师】 李春峰；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2010， 硕士

【摘要】 磁脉冲焊接(Magnetic Pulse Welding/MPW)是一种基于电磁成形的固相连接技术。将MPW应用于铝合金-钢等异种材料的管-管焊接有利于实现零件轻量化结构设计。本文在对工艺参数解析的基础上,采用数值模拟和试验研究相结合的方法,对获得铝合金-钢管件磁脉冲焊接接头的条件和主要参数的影响规律进行了系统研究。首先给出了磁脉冲焊接工艺参数的解析计算流程,得出磁脉冲焊接系统参数对接头连接效果的影响规律,结果表明:降低系统电感,提高等放电能量条件下的电压,可以提高磁场力载荷值和加载速率,并降低能量损耗,因此有利于磁脉冲焊接工艺的实现。采用类比的方法,引入爆炸焊接工艺中流动限、形成波形界面临界速度作为衡量磁脉冲焊接形成条件和焊接效果的判断标准,分析得到碰撞速度和碰撞角度是形成磁脉冲焊接的关键因素。建立了管-管磁脉冲焊接系统的有限元分析模型,采用半耦合法处理脉冲磁场力作用下的管件变形、冲击碰撞过程主要涉及到的磁场与变形耦合问题。以碰撞速度为标准,参照碰撞过程中连接管件运动和变形加速度的变化,评价了各工艺参数对接头焊接效果的影响。数值模拟分析结果表明:减少线圈匝数,提高等放电能量条件下的电压,选择合理的工件间隙均可以提高碰撞速度,有利形成磁脉冲焊接接头。用试验方法探索了中低固有频率电磁成形设备实现磁脉冲焊接的途径,即选用低电感的成形连接系统,采用电压值“窗口”的上限,通过优化接头搭接区径向间隙及其与线圈的相对位置,创造获得焊接接头的有利条件。通过单向拉伸和连接区的剥离试验,检验了连接接头的力学性能,在放电电压5.5 kV、电容量720μF、直径20 mm的5匝线圈的条件下得到了连接强度高于铝合金母材的连接接头。用扫描电镜对3A21铝合金和20#钢管-管磁脉冲焊接接头的微观形貌和成分进行了分析。结果表明:焊接接头上存在宽度不等的趋于平直过渡区,铝钢界面附近的钢的晶粒发生了明显的塑性变形,在过渡区内铁铝元素发生了互扩散,并且铁元素向铝基体内扩散的距离大。更多还原

【Abstract】 Magnetic pulse welding (MPW) is a solid-state joint technology based on electromagnetic forming. Feasible design of lightweight components can be achieved by using MPW technology for dissimilar metals tube such as aluminum and steel. In this work, based on theoretical analysis of the parameters, the necessary conditions for obtaining the MPW joints between aluminum and steel and main parameters affecting them were investigated through numerical simulation and experiments.By theoretical analysis, firstly, a calculation procedure for MPW was proposed. And the effects of main parameters of the forming system on the MPW joints were obtained. The results show that reducing system inductance and increasing the discharge voltage under the equivalent discharge energy can be utilized to improve magnetic force and loading rate, reduce energy loss, so as to facilitate the realization of MPW process.By analogical method, the explosive welding process parameters: flow limit, the critical formation velocity of the fluctuant interface were introduced to evaluate the formation conditions and joining quality of MPW joints. It is obtained that the impact velocity and angle are the key factors to the formation of MPW.Finite element model was established for MPW of aluminum and steel tubes. Semi-coupled method was chosen to solve the coupling field problem between magnetic field and deformation. The impact velocity and acceleration were chosen to measure the effects of all parameters on the MPW during the collision. Simulation results show that reducing the turn number of coil, increasing the discharge voltage under same energy, choosing a reasonable workpiece gap can enhance the collision velocity and facilitate the realization of MPW.The ways to achieve magnetic pulse welding joints by a equipment with the low nature were explored experimentally. Using the low-inductance forming system, adopting the upper discharge voltage, optimizing the radial gap between the workpieces and joining pairs and the coil can be utilized to create favorable conditions for welding. By the uniaxial tensile and the peel test, the mechanical properties of the MPW joints were verified. Under discharge voltage 5.5kV and capacitance 720μF, a coil of five turns with inner diameter 20 mm was used to perform the MPW process, by which a joint whose strength is larger than the aluminum base metal is obtained.The morphology and composition of dissimilar materials joints of 3A2l aluminum and 20 steel was analyzed by SEM. The results show that there is a approximate flat transition zone between aluminum and steel, whose width is not uniform. The diffusion of Fe and Al was investigated in the transition zone. Diffusion depth from Fe to AL is larger than that from AL to Fe.更多还原