Titanium alloys have been widely used in aerospace and other fields due to their 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 the thermal deformation process parameters.

Application of simulation technology in the field of titanium alloy hot working

Titanium alloys usually need to be hot-worked in β single-phase region or α β two-phase region to obtain products with certain structure and properties. The choice of hot working parameters has an important impact on the machining properties and microstructure of titanium alloys. In recent years, domestic research in the field of titanium alloy hot working is increasing day by day. Among them, the application of thermal simulation technology and numerical simulation technology in the thermal deformation mechanism and microstructure evolution of titanium alloy is particularly prominent.

应用 Typical application of thermal simulation technology

Many scholars performed thermal compression deformation experiments on different types of titanium alloys using thermal / force simulation test machines, and obtained the material's flow stress curve, that is, the stress-strain relationship. The flow stress curve reflects the internal relationship between the flow stress and the deformation process parameters, and it is also a macro manifestation of the change in the internal structure of the material. Xu Wenchen and others performed a constant strain rate compression deformation test on a thermal simulator to study the dynamic thermal deformation behavior of TA15 titanium alloy. The deformation activation energy Q of the material was calculated and the thermal deformation structure was observed. Dynamic recrystallization in the alpha phase region is the main softening mechanism of the material, while the softening mechanism in the beta phase region is dominated by dynamic recovery.

Typical application of numerical simulation technology

Because the numerical simulation technology enables the titanium alloy hot working process to be truly reproduced on a computer, both manufacturers and scientific researchers use this technology to study the relationship between ideal process parameters and 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. Shao Hui [11] et al. Studied the evolution of α phase of TC21 titanium alloy with lamellar structure during the two-phase zone forging. The DEFORM software was used to simulate the change of temperature and strain fields during forging and quantitatively analyze the morphological changes of the α phase. The smaller the Feret Ratio, the morphology tends to be spheroidized. The results show that the strain field and temperature field affect the evolution of flake phases. Under lower strain conditions, the temperature of the edge of the forging material decreases rapidly, recrystallization is sufficient, and the temperature at the center of the forging material is high.

 Study on simulation of microstructure evolution

The microstructure diversity of titanium alloy has a regular relationship with the multi-step production process of titanium alloy and the diversity of each process. This complex connection makes it difficult to predict and control the microstructure and properties of titanium alloys with traditional methods. 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 between the main process parameters on the macro and microstructure of the hot formed workpiece. Using numerical simulation technology to reproduce the evolution of microstructure can not only deepen the understanding of the mechanism of tissue change and promote the development of existing theories, but also improve the structure of materials and optimize the preparation process of materials, so as to obtain the expected mechanical properties of materials.

Compared with the traditional process trial and error method, the use of simulation technology as a research and development method can shorten the development cycle, reduce production costs, and optimize the production process, thereby achieving the purpose of improving production efficiency and increasing economic benefits. However, due to the high price and long production cycle of titanium alloys, the research of its production process urgently needs simulation technology to open up shortcuts to overcome the problems of narrow thermal processing temperature range and complex and diverse process-structure-performance relationships.

A lot of research work has been carried out on the thermal deformation mechanism and microstructure evolution of titanium alloys using thermal simulation technology and numerical simulation technology at home and abroad. The results of the relationship between force and energy parameters, process parameters, and microstructure can be used to optimize production processes, The role and effect of improving product quality. However, due to the inaccurate material performance data, the boundary conditions and friction parameters are difficult to be close to reality, and the study of macro variables does not involve changes in microstructure, the simulation results have certain errors compared with actual production.

Future research on the thermal deformation mechanism and microstructure evolution of titanium alloys must combine physical simulation technology and numerical simulation technology to establish a macro-finite element model that is more in line with the actual production process, and couple it with the microstructure evolution model to strive for simulation results Not only can it provide a theoretical basis for on-site production, but it can also quantitatively guide the on-site process, and finally achieve the purpose of tracking the deformation process in real time and controlling product quality.

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