Titanium Alloy Structure Diversity And Processing Technology
Titanium alloys usually require thermal processing in the β single-phase zone or α+β two-phase zone to obtain products with certain structure and properties. The selection of thermal processing parameters has an important impact on the processing properties and microstructure of titanium alloys. In recent years, domestic research in the field of titanium alloy thermal processing has increased day by day, and the application of thermal simulation technology and numerical simulation technology in titanium alloy thermal deformation mechanism and microstructure evolution law is particularly prominent.
Titanium alloy has been widely used in aerospace and other fields due to its excellent properties such as low density, high specific strength and creep resistance. Titanium alloy has the characteristics of low ductility, large deformation resistance and obvious anisotropy. Therefore, titanium alloy is very sensitive to thermal deformation process parameters. This article introduces the physical simulation technology and numerical simulation technology and its application in the field of titanium alloy thermal processing. It focuses on the application status of simulation technology in titanium alloy hot deformation mechanism, prediction and control of defects and microstructure evolution, and points out the problems to be solved and development trends in the current titanium alloy hot forming simulation.
With the close integration of traditional plastic processing technology and modern computer technology in all directions, traditional empirical design methods are quickly and effectively replaced by analog design. Before designing and determining the plastic forming process, certain predictive data or results must be available, and process simulation is usually required. This kind of simulation before actual production is generally divided into physical simulation and numerical simulation. Typical applications of thermal simulation technology.
1. Many scholars have conducted thermal compression deformation experiments on different types of titanium alloys using thermal/force simulation test machines, and obtained the flow stress curve of the material, that is, the stress-strain relationship. The flow stress curve reflects the internal relationship between the flow stress and the deformation process parameters, and at the same time, it is also the macroscopic manifestation of the internal structure of the material. Xu Wenchen [3] conducted a constant strain rate compression deformation test on a thermal simulator to study the dynamic thermal deformation behavior of TA15 titanium alloy, calculated the deformation activation energy Q of the material, and observed the thermal deformation structure. Dynamic recrystallization in the α phase region is the main softening mechanism of the material, while in the β phase region the softening mechanism is dominated by dynamic recovery. As the deformation rate decreases.
2. Typical applications of numerical simulation technology. Because the numerical simulation technology enables the titanium alloy thermal processing process to be truly reproduced on the computer, enterprise producers and scientific researchers use this technology to study the relationship between ideal process parameters and the corresponding organization and mechanical properties to optimize the current production process and The purpose of reducing the development cost of new products, new processes and new materials. Et al. studied the evolution of α-phase in the forging process of TC21 titanium alloy with lamellar structure in the two-phase zone. The simulation and analysis of the change law of temperature field and strain field during the forging process and quantitative analysis of the smaller the change of the morphology of the alpha phase, the morphology tends to spheroidize. The results show that the strain field and temperature field affect the evolution of the flaky phase. Under the condition of lower strain, the edge of the forging material will be recrystallized rapidly due to the rapid temperature drop, and the temperature of the center of the forging material will be higher.
The diversity of the microstructure of titanium alloys has a regular relationship with the multi-process production process of titanium alloys and the diversity of each process. This complex connection determines that traditional methods are difficult to predict and control the structure and properties of titanium alloys. With the development of computer and numerical simulation technology in recent years, the numerical simulation method of microstructure has become a powerful tool to obtain the quantitative relationship of the influence of main process parameters on the macroscopic and microstructure of hot formed parts. The use of numerical simulation technology to reproduce the evolution of the microstructure can not only deepen the understanding of the mechanism of structure change, promote the development of existing theories, but also improve the structure of the material and optimize the preparation process of the material, thereby obtaining the expected mechanical properties of the material.
