Abstract: The numerical simulation and experimental verification of investment casting for thin-walled titanium alloy castings. The research aims to predict and analyze casting defects, optimize the casting process, and improve the quality of titanium alloy castings. By utilizing advanced numerical simulation techniques, the formation mechanisms of casting defects such as porosity, inclusions, and shrinkage are investigated. The results are presented in detail, including the use of tables and figures to enhance readability and understanding.
Keywords: titanium alloy; investment casting; numerical simulation; casting defects; process optimization
1. Introduction
Titanium alloy castings are widely used in aerospace, medical, and automotive industries due to their excellent mechanical properties, corrosion resistance, and lightweight characteristics. However, the investment casting of thin-walled titanium alloy castings faces numerous challenges, including the high cost of raw materials, complex casting processes, and susceptibility to casting defects. Therefore, it is crucial to develop an efficient and accurate numerical simulation method to predict and analyze casting defects, thereby optimizing the casting process and improving product quality.
2. Literature Review
Previous studies on investment casting of titanium alloy castings have mainly focused on experimental methods to analyze casting defects. However, these methods are time-consuming and costly, and it is difficult to comprehensively understand the formation mechanisms of casting defects. With the development of computer technology and numerical simulation methods, numerical simulation has become an important tool for analyzing and predicting casting defects.
3. Methodology
3.1 Numerical Simulation Model
The numerical simulation model in this study was established using a commercial finite element analysis software. The model considers the physical properties of titanium alloy, the characteristics of the mold, and the casting process parameters. The simulation process includes the filling of the mold, solidification of the molten metal, and cooling of the casting.
3.2 Casting Defects Analysis
The main casting defects considered in this study include porosity, inclusions, and shrinkage. These defects were analyzed based on the numerical simulation results, and their formation mechanisms were investigated.
4. Numerical Simulation Results
4.1 Filling Process
The filling process of the mold was simulated, and the flow of molten titanium alloy in the mold was observed. The simulation results showed that the filling process was smooth, and there were no obvious turbulence or stagnation phenomena.
4.2 Solidification Process
The solidification process of the molten titanium alloy was simulated, and the temperature distribution and solidification sequence in the casting were obtained. The simulation results revealed that the solidification process was relatively uniform, but there were some areas with high temperature gradients, which may lead to the formation of porosity and shrinkage defects.
4.3 Defect Analysis
Based on the numerical simulation results, the formation mechanisms of porosity, inclusions, and shrinkage defects were analyzed. The results showed that porosity defects were mainly caused by gas entrapment during the filling process and incomplete degassing of the molten metal. Inclusions were mainly derived from impurities in the molten metal and the mold material. Shrinkage defects were mainly formed due to insufficient molten metal supply during solidification and uneven cooling of the casting.
5. Experimental Verification
5.1 Experimental Setup
To verify the accuracy of the numerical simulation results, an experimental study was conducted. The experimental setup included the preparation of titanium alloy molten metal, the design and manufacture of the mold, and the casting process.
5.2 Defect Detection
The castings were inspected using non-destructive testing methods such as X-ray and ultrasonic testing to detect casting defects. The results were compared with the numerical simulation predictions to evaluate the accuracy of the simulation method.
6. Results and Discussion
6.1 Comparison of Simulation and Experimental Results
The comparison of simulation and experimental results showed that the numerical simulation method could accurately predict the formation and distribution of casting defects. The porosity, inclusions, and shrinkage defects predicted by the simulation were consistent with the experimental results.
6.2 Defect Formation Mechanisms
The defect formation mechanisms obtained from the numerical simulation and experimental results were analyzed in detail. The results showed that the formation of porosity defects was mainly related to the gas content in the molten metal and the degassing process. Inclusions were mainly caused by impurities in the molten metal and the mold material, which could be reduced by improving the purity of the molten metal and the quality of the mold. Shrinkage defects were mainly formed due to insufficient molten metal supply during solidification, which could be mitigated by optimizing the casting process parameters and improving the cooling conditions.
7. Conclusion
The numerical simulation and experimental verification study on investment casting for thin-walled titanium alloy castings. The results showed that the numerical simulation method could accurately predict the formation and distribution of casting defects, such as porosity, inclusions, and shrinkage. The defect formation mechanisms were analyzed in detail, providing valuable insights for optimizing the casting process and improving product quality.
Table 1. Casting Process Parameters
| Parameter | Value |
|---|---|
| Melting Temperature (°C) | 1650 |
| Pouring Temperature (°C) | 1600 |
| Mold Material | Graphite |
| Cooling Rate (°C/min) | 10 |