双金属轧制连接的多参数影响规律研究

【作者】 杜天柏；

【导师】 严珩志；

【作者基本信息】 中南大学 ， 机械设计及理论， 2004， 硕士

【摘要】 材料的复合,尤其是异种金属材料的复合,为多功能材料的开发提供了一个新技术途径。采用轧制工艺生产双金属产品,优于爆炸焊、扩散焊等工艺,是一种十分经济实用的方法。轧制复合工艺经历了热轧复合、等辊冷轧复合、肆步轧制复合等阶段。因轧制过程金属变形的复杂性,其理论研究处于探索完善阶段。本文试图探讨双金属轧制连接的机理,对轧制连接进行理论分析,探寻轧制参数对轧制连接的影响规律,找出合理的轧制条件。 1.本文首先分析了双金属轧制的塑性变形连接机理,提出界面上下层金属均发生塑性变形时即为轧制连接点位置的假定,随后以金属屈服变形为判据,针对轧制双金属夹片的连接,采用主应力法,推导出了金属界面连接点位置、中性点位置和轧后厚度比等参数的理论模型,并通过改变轧制条件参数,找出了连接率、轧后厚度比随轧制条件的变化关系。 2.运用大型有限元软件MARC,建立轧制模型,编写过程文件,设置不同的轧制条件参数。在不同的轧制变形率、金属材料、轧制速度、轧辊与轧件及轧件相互问的摩擦环境等条件下进行仿真,获得了轧制连接率和轧后厚度比的值,得出了与工程法分析相近的结论。同时,运用MARC对双金属轧制仿真,可以得到轧制过程界面受力、塑性变形等数值分布。 3.进行了双金属轧制的实验,通过与理论分析结果对比,认为仿真分析比工程法分析更精确。 通过工程法分析、MARC仿真分析和实验研究,本文对双金属轧制连接得到了以下结论和认识:①两种金属材料屈服强度越相近,轧制连接率越大,若金属材料的屈服强度差异过大,则不会连接;②变形率越大,连接长度就越大,但连接率随变形率增加,呈先增后降的趋势,说明有一最佳轧制变形率;③金属界面摩擦系数越大越有利于连接;④轧制外硬内软双金属夹片,轧后覆层厚度比随两种金属的屈服强度差异增大而增大;⑤轧制连接率随轧制速度的增加而减小,因而轧制速度相对小些有利于轧制连接。更多还原

【Abstract】 Complex of materials, especially complex of different kind of metals, have provided a new approach for developing the new merits of material. The rolling process is efficient and economical to other types of processes, such as explosive cladding, diffusion welding, etc. The rolling processes have developed from hot-roll bonding technique to cold-roll bonding technique and asynchronous roll bonding technique. Because of the complexity of rolling at the roll gap, the theory research of rolling processes is in exploring stage. In this text, the bonding mechanism of bimetal is attempted to inquire into and carry on theoretical analysis to bonding, and find out the reasonable rolling condition.At first, the mechanism of bimetal roll-bonding about the plastic deformation has been analyzed in this text, and assumes that the point of the bonding of interface occur when both of upper and lower at interface metals take place of the plastic deformation. Then, with mean shear yield stresses of the metal is the criterion , using the slab method, the model has derived out the mathematical expressions, such as the bonding point ,the neutral points and the thickness ratio of upper layer to the sandwich sheets after rolling. By way of the change rolling condition parameters, has found out the relation between the bonding rate and the thickness ratio of upper layer to the sandwich sheets after rolling.Second, using large-scale finite element method software—MARC establishes the rolling model, and compiles the process file, and sets up the different rolling condition parameters. I carried on simulation under the different conditions, such as reduction of rolling ratio, different metals, changing of rolling speed, frictional factors of the roller and layer, and so on. We can gain the bonding rate and the thickness ratio of upper layer to the sandwich sheets after rolling, and conclude the close conclusion with the analysis of the slab method. At the meantime, using the MARC software can directly receive the numerical distributing of rolling power and plastic deformation from MARC’s RESULTS.Third, the experiment of bimetal rolling has been done, and throughthe comparisons, the simulation is more accurate than the slab method.By way of comparisons of the slab method, simulation of MARC and researching of experiment, the following conclusion and knowledge have been reached in the text: CD The roll bonding rate increase with the increase in the rate of mean shear yield stresses of clad and core layer metal, but if the rate of mean shear yield stresses of clad and core layer metal is too small, the roll bonding point can not be found;(2)Contact length increase with the increase in the reduction, but the relative bonding length don’t comply increase with the increase in the reduction, increases first and then decreases with increasing reduction, so the maximum value for relative bonding length must occurs;(3)The relative bonding length increase with the increase in the frictional factor; (4) As the shear yield stress increase, the thickness of sandwich sheet at the exit is larger; ?The relative bonding length decreases with the increase in the rolling speed, it is said that smaller rolling speed benefit the roll bonding.更多还原