王会照,王玉玲,姜芙林,杨发展,杨勇,马保山,梁鹏.激光重熔对TC4钛合金表面Al2O3-ZrO2激光熔覆层形貌组织、元素分布和裂纹敏感性的影响[J].表面技术,2022,51(12):380-391.
WANG Hui-zhao,WANG Yu-ling,JIANG Fu-lin,YANG Fa-zhan,YANG Yong,MA Bao-shan,LIANG Peng.Effects of Laser Remelting on Morphology, Microstructure, Element Distribution and Crack Sensitivity of Al2O3-ZrO2 Laser Cladding Layer on TC4 Titanium Alloy[J].Surface Technology,2022,51(12):380-391 |
| 激光重熔对TC4钛合金表面Al2O3-ZrO2激光熔覆层形貌组织、元素分布和裂纹敏感性的影响 |
| Effects of Laser Remelting on Morphology, Microstructure, Element Distribution and Crack Sensitivity of Al2O3-ZrO2 Laser Cladding Layer on TC4 Titanium Alloy |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.12.039 |
| 中文关键词: 激光重熔 有限元分析 形貌组织 元素分布 裂纹敏感性 |
| 英文关键词:laser remelting finite element analysis morphology and structure element distribution crack sensitivity |
| 基金项目:山东省重点研发计划(2019GNC106102);山东省自然科学基金(ZR2019MEE05，ZR2021ME198);高等学校学科创新引智计划(D21017) |
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| Author | Institution |
| WANG Hui-zhao | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China |
| WANG Yu-ling | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China |
| JIANG Fu-lin | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China |
| YANG Fa-zhan | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China |
| YANG Yong | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China |
| MA Bao-shan | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China |
| LIANG Peng | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China |
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| 中文摘要: |
| 目的 减少裂纹数目，改善TC4合金基体表面激光熔覆涂层的表面形貌和裂纹敏感性。方法 采用激光重熔工艺对激光熔覆后的熔覆层进行后处理。通过有限元与试验相结合的方法，研究激光重熔处理对Al2O3-ZrO2熔覆层表面形貌、组织演变及裂纹敏感性的影响规律，并探讨其影响机理。激光熔覆完毕后，再次进行激光扫描，得到重熔涂层，并采用扫描电镜和维氏硬度计对激光熔覆与激光重熔涂层的熔覆形貌、微观组织、裂纹情况、元素分布及断裂韧性进行观察与测试。结果 有限元仿真结果表明，熔覆涂层从热影响区到熔覆层顶部的温度由660.23 ℃升至3 122.3 ℃，激光重熔涂层温度则是由927.61 ℃升至2 772.9 ℃。此外，重熔涂层在Z方向上的残余应力明显下降，且残余应力曲线平缓，应力梯度较小。激光重熔工艺可以明显缓解熔覆涂层结合区的温度梯度和残余应力。通过对涂层进行观察检测发现，激光重熔涂层表面起伏状况得到缓解，表面裂纹数目减少。重熔涂层平面晶数量较少，组织致密，使得裂纹发生穿晶扩展，裂纹扩展能量不断消耗，有效阻碍了裂纹延拓。激光重熔工艺可以均化元素分布，使重熔涂层的断裂韧性提升至9 MPa.m1/2以上，有效提高了涂层的断裂韧性，改善裂纹的敏感性。结论 通过激光重熔，熔覆层表面起伏变小，裂纹数目明显减少，断裂韧性和结合强度得到明显提高。 |
| 英文摘要: |
| TC4 (Ti-6Al-4V) titanium alloy has the characteristics of high specific strength and good heat resistance. With the same quality, titanium alloy has better mechanical properties than other metals, and is widely used in aviation, aerospace and navigation etc. but its characteristics of poor wear resistance and low hardness limit its wide application. Due to the good hardness, wear resistance and corrosion resistance of ceramic materials, ceramic-metal bonding has become a research hotspot. In recent years, laser cladding, as a new surface modification technology, has provided a new bonding method for metal-ceramic bonding. The work aims to reduce the number of cracks to improve the surface morphology and crack sensitivity of laser cladding coating on TC4 alloy substrate. Laser remelting process was used to treat the cladding layer after laser cladding. The effects of laser remelting on the surface morphology, microstructure evolution and crack sensitivity of Al2O3-ZrO2 cladding layer were studied by combining finite element method with experimental method, and the influence mechanism was also discussed. After laser cladding, the remelting coating was obtained by laser scanning again, and the cladding morphology, microstructure, crack, element distribution and fracture toughness of laser cladding and remelting coating were observed and tested with scanning electron microscope and Vickers hardness tester. Finite element simulation results showed that the temperature of cladding coating rose from 660.23 ℃ to 3 122.3 ℃ from heat affected zone to the top of cladding layer, and the temperature of laser remelting coating rose from 927.61 ℃ to 2 772.9 ℃. By comparing the temperature difference per unit distance, the temperature gradient of remelting coating was smaller than that of cladding coating. In addition, in the Y direction, the residual stress gradually rose from the center to the edge of the coating, while in the Z direction, the residual stress of the remelted coating was obviously relieved, and the residual stress curve was gentle, and the stress gradient was small. Therefore, the laser remelting process can obviously relieve the temperature gradient and residual stress in the bonding zone of the cladding coating. It was found that the surface undulation of laser remelting coating was relieved and the number of surface cracks was reduced. When observing the microstructure of the coating, it was found that the cracks originated from the planar crystal, and several microcracks followed the planar crystal path which consumed the least energy of crack propagation, and finally converged to form the main crack. In this process, the crack energy accumulated continuously, while the plane crystal quantity of the remelting coating was small and the microstructure was dense, which lead to the transgranular propagation of the crack, and the energy consumption of the crack propagation was constant, which effectively hindered the propagation of the crack. The laser remelting process can homogenize the distribution of elements in the top, middle and bottom regions, and increase the fracture toughness of the remelting coating to more than 9 MPa.m1/2, which effectively improved the fracture toughness of the coating and improved the crack sensitivity. By laser remelting, the surface undulation of cladding layer becomes smaller, the number of cracks decreases obviously and the fracture toughness and bond strength are improved obviously. |
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