| YIN Yanheng,ZHAO Zhen,LI Qing,LIU Dameng,LI Weiqing.Investigation of Wear Properties of Titanium Alloy Surfaces Polished with Continuous Laser[J],54(1):218-227 |
| Investigation of Wear Properties of Titanium Alloy Surfaces Polished with Continuous Laser |
| Received:March 04, 2024 Revised:April 10, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.01.020 |
| KeyWord:laser polishing titanium alloy polishing process surface roughness friction coefficient wear resistance |
| Author | Institution |
| YIN Yanheng |
School of Engineering and Technology, China University of Geosciences Beijing, Beijing , China |
| ZHAO Zhen |
Jihua Laboratory, Guangdong Foshan , China |
| LI Qing |
Jihua Laboratory, Guangdong Foshan , China |
| LIU Dameng |
School of Mechanical Engineering, Tsinghua University, Beijing , China |
| LI Weiqing |
School of Engineering and Technology, China University of Geosciences Beijing, Beijing , China |
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| Abstract: |
| The work aims to investigate the influence of continuous laser parameters on friction wear performance and polishing precision of Ti6Al4V polished surfaces, and reveal the key technologies and deep physical mechanisms behind precision polishing and wear performance enhancement of titanium alloy surfaces through the control of laser parameters, so as to meet the stringent requirements for high-performance materials in aerospace, medical devices, and other advanced application fields. Continuous laser polishing technology was employed for the detailed treatment of Ti6Al4V titanium alloy surfaces. By varying experimental conditions, including defocus distance, laser power, and scanning speed, the specific influence of laser parameters on the titanium alloy's surface morphology, surface roughness, and friction coefficient was systematically examined. Employing a suite of characterization tools such as high-resolution ultra-depth-of-field microscopy, metallographic microscopy, white-light interferometry, and friction wear testing, the research offered comprehensive insights into the changes induced on the alloy surfaces by laser polishing. Findings demonstrated that the surface roughness of the Ti6Al4V titanium alloy was significantly reduced to 0.412 μm, marking an approximate 87% reduction, while the friction coefficient found a decrease of about 16%. The core of the investigation was the precision in adjusting laser parameters to optimize the balance between energy distribution and material interaction, leading to significant enhancements in surface quality. Theoretical analysis further revealed the crucial roles of thermal capillary effect control and grain refinement mechanisms in surface treatment, highlighting their decisive impact on improving material polishing effects and reducing friction coefficients. By optimizing continuous laser parameters (power P=30 W, scanning speed v=1 000 mm/s, defocus distance z=2 mm, beam diameter d=0.035 mm), continuous laser polishing technology not only significantly reduced the surface roughness of titanium alloys but also effectively enhanced their friction wear performance. The surface roughness of the polishing interface was intricately linked to the melt pool's temperature, predominantly governed by laser power density or the laser's power distributed over a unit area. Considering that laser power density was determined by both the spot area and the power, the defocusing distance, power, and speed each directly impacted the spot size, power input, and the quantity of laser energy received by a unit area over a specified time period, respectively. Consequently, variations in laser parameters in experiments involving defocus, power, and speed essentially constituted adjustments to the spatial and temporal distribution of laser power density. The experimental setup utilized a Gaussian beam, characterized by a higher energy density at its center tapering off towards the edges. Optimal surface polishing effects were achieved when the spatial and temporal power density was appropriately adjusted, ensuring that the energy disparity between the beam's center and its edges - the temperature gradient in the melted material-substantially decreased. This adjustment led to a smaller temperature differential within the melt pool, fostering relatively stable melt pool dynamics. Conversely, excessive power density elevated the center's energy density and the melt pool's temperature, widening the temperature gap between the pool and its periphery. This discrepancy prompted the molten material to shift dramatically from the center towards the edges, resulting in pronounced melt tracks and increased roughness. At lower power densities, the melting process was insufficient, yielding suboptimal polishing outcomes. This research provides a new surface treatment strategy for the application of Ti6Al4V titanium alloy in fields demanding high surface performance, such as aerospace and medical devices. |
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