| BIAN Hongyou,TAN Yukai,LIU Weijun,LI Qiang,WANG Wei.Effect of Inter-channel Cooling on Microstructure and Properties of CoCrW Coating Deposited by Laser on DD5 Single Crystal[J],54(9):164-174 |
| Effect of Inter-channel Cooling on Microstructure and Properties of CoCrW Coating Deposited by Laser on DD5 Single Crystal |
| Received:August 30, 2024 Revised:February 13, 2025 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.09.014 |
| KeyWord:laser technology laser deposition CoCrW inter channel cooling microstructure mechanical properties wear resistance |
| Author | Institution |
| BIAN Hongyou |
School of Mechanical Engineering, Shenyang University of Technology, Shenyang , China |
| TAN Yukai |
School of Mechanical Engineering, Shenyang University of Technology, Shenyang , China |
| LIU Weijun |
School of Mechanical Engineering, Shenyang University of Technology, Shenyang , China |
| LI Qiang |
School of Mechanical Engineering, Shenyang University of Technology, Shenyang , China |
| WANG Wei |
School of Mechanical Engineering, Shenyang University of Technology, Shenyang , China |
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| Abstract: |
| DD5 alloy, a second-generation nickel-based single crystal superalloy independently developed by China, is renowned for its exceptional mechanical properties under high-temperature and high-pressure conditions. Therefore, it has not only been widely used in the production of single crystal turbine blades for aircraft engines, but also received extensive attention from scholars at home and abroad. But, the tooth crown area of DD5 single crystal alloy turbine blades is prone to wear, and a wear-resistant layer is prepared by laser deposition technology to enhance its wear resistance. However, the process characteristics of laser deposition technology, which melts and accumulates layer by layer, determine that the processing technology will have an impact on the formed wear-resistant layer. As a result, during the laser continuous deposition process, inter channel cooling is incorporated to decrease the heat buildup from the laser continuous deposition, and investigate its impact on the CoCrW wear-resistant layer produced through laser deposition. During the experiment, CoCrW metal powder is utilized for laser deposition, while DD5 single crystal alloy serves as the substrate. The cylindrical specimen has a diameter of 18 mm and a thickness of 4 mm. The mobility of the equipment is facilitated by the KUKA six axis robotic arm. Additionally, an IPG fiber laser with a wavelength of 1 070 nm and a maximum power of 6 000 W is employed for the laser processing. By employing laser deposition manufacturing technology, a wear-resistant CoCrW alloy layer is applied to the surface of DD5 single-crystal alloy. It aims to investigate the impact of inter-channel cooling on the structural characteristics of the laser deposition process, with consideration given to whether or not to implement the cooling method during deposition. A comparison of the distribution pattern of microhardness, friction and wear properties is made after analyzing the arborization of the deposited layer's microstructure, as well as extending the cooling time during the deposition process to change the deposition temperature. After cooling between the filling channels for 60 seconds to room temperature, the surface temperature is about 37 ℃, and the height of the wear-resistant layer decreases overall, making the macroscopic morphology smoother. The composition category of dendrites in the wear-resistant layer does not change significantly. The bottom primarily features columnar crystals, the middle is a mix of disordered columnar crystals and a few equiaxed crystals, while the top is predominantly made up of equiaxed crystals. After cooling, the inter layer remelting zone and the inter channel remelting zone of the CoCrW wear-resistant layer shows a marked decrease in coarsened grains, thus leading to an overall grain refinement of the layer with a more condensed arrangement. The strengthening phases of CoCx, M7C3, and M23C6 carbides increase. After cooling, the average hardness of the CoCrW wear-resistant layer increase from 477HV0.5 to 534HV0.5, with a hardness increase of 11.95%. The coefficient of friction plummets from 0.4 to 0.35, and the amount of wear drops from 4.8 g to 4.0 g. The CoCrW wear-resistant layer after inter channel cooling reduces the heat accumulation caused by continuous laser deposition, resulting in grain refinement in the remelted zone, thereby improving the hardness and wear resistance of the wear-resistant layer. |
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