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| Temperature Field Prediction and Microstructure Analysis of Gradient TC4/TC11 Titanium Alloy Deposited by Laser Additive Manufacturing |
| SUN Cheng1, SUN Yizhang1, LIU Jin2, ZHANG Jikui1,3 |
1. School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China;
2. School of Material Science and Engineering, Beihang University, Beijing 100191, China;
3. National Engineering Laboratory of Additive Manufacturing for Large Metallic Components,Beihang University, Beijing 100191, China |
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Abstract A typical specimen of TC4/TC11 titanium alloy gradient material was deposited by laser additive manufacturing technology. The temperature history of the three characteristic positions during the deposition process was measured and the microstructure of the deposited sample was observed. A finite element model for temperature field prediction of laser additive manufacturing TC4/TC11 gradient material structure was established. The results of the temperature field calculation of the finite element model are in good agreement with the experimental results. And the Tβ temperature transition line position calculated by the finite element model is in good agreement with the observation results in the microstructure of the sample. The microstructure observation shows that there is no defect in the sample. The top area is equiaxed grain region, and there is a columnar crystal region through the whole material increasing area from the bottom to the equiaxed crystal region. The microstructure on both sides of the Tβ temperature transition line is significantly different: during the process of finishing the last layer, the area where temperature exceeds Tβ produces ultrafine α+β basket wave microstructure, and will produce α+β basket wave microstructure with a mass of α clusters if the temperature is below Tβ. The microstructure is continuous and no mutation at the design interface (material composition change position).
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2018, 
