TA15/YG8复合管扩散复合工艺设计及其施压阶段的有限元模拟

Development of Diffusion Bonding Process and Finite Element Simulation for the Pressure Stage of TA15/YG8 Composite Tube

目的以制备钛合金/硬质合金叠层复合管为目标,基于钛合金和硬质合金的性能特点,解决使异种管材相互靠近的载荷难以直接施加的问题,设计开发钛合金/硬质合金复合管的扩散复合工艺。方法借鉴颗粒介质成形的基本原理,提出一种钛合金管-硬质合金管扩散复合方法,并以TA15钛合金和YG8硬质合金为原材料,通过有限元模拟研究了管间间隙、固体颗粒的填充度、固体颗粒的尺寸和管坯长径比等工艺参数对扩散复合施压过程中TA15钛合金管/YG8硬质合金管界面上径向应力分布的影响。结果有限元模拟结果表明,本文设计提出的钛/硬质合金异质管制备工艺确实能将轴向压力转变为径向贴合力,并且可以通过调控下压量满足扩散复合的压力需求(最小径向应力大于10 MPa)。沿轴线方向,钛合金管与硬质合金管之间的径向应力呈不均匀分布,并且受到管间间隙、颗粒填充度、颗粒的尺寸、管坯长径比等参数的影响。管间装配精度越高、固体颗粒尺寸越小、固体颗粒的填充度越多,越有益于管坯之间的扩散复合。试验结果表明,TA15钛合金/YG8硬质合金复合管在不同部位皆实现了良好的冶金结合。结论设计开发了一种钛合金/硬质合金复合管扩散复合方法,制备出具有良好冶金结合界面的TA15钛合金/YG8硬质合金复合管。

With the goal of fabricating titanium alloy/cemented carbide laminated composite tubes,based on the characteristics of titanium alloy and cemented carbide,the work aims to solve the problem that it is difficult to directly apply the load that makes dissimilar tubes close to each other,and develop a diffusion bonding process for titanium alloy/cemented carbide composite tubes.According to the basic principle of granular media forming,a diffusion bonding method to fabricate titanium alloy/cemented carbide composite tube was proposed.TA15 titanium alloy and YG8 cemented carbide were used as raw materials.The effects of process parameters such as inter-tube gap,filling degree of solid particles,size of solid particles,and length-to-diameter ratio of the tube billet on the distribution of the radial stress on the interface between the TA15 titanium alloy tube and the YG8 cemented carbide tube in the pressure process were studied by finite element simulation.The finite element simulation results showed that the proposed titanium/cemented carbide composite tube fabrication process could indeed transform the axial pressure into radial stress and could meet the required stress(the minimum radial stress was 10 MPa)to achieve diffusion bonding by regulating the amount of downward displacement.Along the axial direction,the radial force between the titanium alloy tube and the carbide tube was unevenly distributed and was affected by parameters such as initial gap between tube billets,height of solid particles,size of solid particles,and length-to-diameter ratio of billet.The higher the assembly precision,the smaller the size of solid particles and the more filling degree of solid particles,the more beneficial the diffusion bonding of heterogeneous tubes.The experimental results showed that the TA15 titanium alloy/YG8 cemented carbide composite tube realized good metallurgical bonding in different regions.A diffusion bonding method of titanium alloy/cemented carbide composite tube is designed and developed,and TA15 titanium alloy/YG8 cemented carbide composite tube with good metallurgical bonding interface is successfully fabricated.