| XU Jin,YANG Jia,CHEN Zhaojian,WANG Chengsong,LI Dongming,SONG Tao,HAN Tian.Microstructure and Wear Resistance of CoCrFeNiMn High Entropy Alloy Coating by Extreme-high Speed Laser Cladding[J],54(3):152-161 |
| Microstructure and Wear Resistance of CoCrFeNiMn High Entropy Alloy Coating by Extreme-high Speed Laser Cladding |
| Received:April 08, 2024 Revised:October 24, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.03.013 |
| KeyWord:extreme-high speed laser cladding high entropy alloy microstructure friction and wear |
| Author | Institution |
| XU Jin |
Jiangsu Hengli Hydraulic Co.Ltd., Jiangsu Changzhou , China |
| YANG Jia |
CCCC Second Harbor Engineering Co.Ltd., Wuhan , China |
| CHEN Zhaojian |
Jiangsu Hengli Hydraulic Co.Ltd., Jiangsu Changzhou , China |
| WANG Chengsong |
Jiangsu Hengli Hydraulic Co.Ltd., Jiangsu Changzhou , China |
| LI Dongming |
Jiangsu Hengli Hydraulic Co.Ltd., Jiangsu Changzhou , China |
| SONG Tao |
Jiangsu Hengli Hydraulic Co.Ltd., Jiangsu Changzhou , China |
| HAN Tian |
School of Mechanical Engineering, Jiangsu University, Jiangsu Zhenjiang , China |
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| Abstract: |
| Modern engineering applications are constantly striving to develop mechanical components with higher performance, better microstructure stability and corrosion resistance, and lower maintenance and repair costs. This requires the widespread use of advanced high-performance materials, such as high entropy alloys (HEAs). HEAs, characterized by an equimolar or approximately equimolar composition of five or more metallic elements, represent a unique class of alloys. Approximately 5%-35% of alloying elements are present in HEAs. HEAs are mainly characterized by high entropy, slow diffusion, severe lattice distortion, and cocktail effect. Due to the advanced microstructure stability, HEAs exhibit better mechanical properties at room temperature, low temperature, and high temperature over a larger temperature range and longer periods of time. The CoCrFeNiMn alloy is a representative example of HEAs, exhibiting superior mechanical properties, corrosion resistance, and wear resistance. Consequently, the fabrication of CoCrFeNiMn protective coatings holds significant potential across various applications. To overcome the limitations of traditional laser cladding processes, the extreme-high speed laser cladding (EHLA) technology has been introduced by Schopphoven and colleagues. EHLA technology has resolved the efficiency challenges of conventional laser cladding methods and has enhanced the performance of the coatings, contributing to the cost-effective utilization of HEAS. In this study, CoCrFeNiMn HEA coatings were fabricated by EHLA at cladding speed of 20 m/min, 30 m/min, and 40 m/min. The phase composition of the powder and coatings were analyzed with an X-ray diffraction analyzer. The microstructures of the coatings were characterized with an optical microscope and a scanning electron microscope. Additionally, the elemental distribution within the coatings was determined with energy-dispersive X-ray spectroscopy. The microhardness of the coatings was measured with a Vickers hardness tester, and the surface friction and wear performance of the coatings were tested with an HT-1000 friction and wear testing machine. A well-formed CoCrFeNiMn HEA coating was successfully prepared by EHLA on the surface of Q355D steel. The test results indicated that the coating exhibited a multi-layered stacking structure, with a rich dendritic microstructure within the layers. As the cladding speed increased, the size and scale of the dendrites within the coating decreased, leading to a finer grain size. Under the effect of heat input, the grain size in the overlapping area slightly coarsened. However, due to the extremely small heat input of high-speed laser cladding on the solidified deposition layer, the degree and area of grain enlargement were very limited. The element distribution inside the coating was uniform without obvious segregation, which made the coating form a more stable and uniform structure, and have better performance. At a cladding speed of 40 m/min, the transition zone between the coating and the substrate was the narrowest, suggesting that an increased cladding speed effectively reduced the dilution rate of the coating. The hardness of the coatings increased with the cladding speed, thereby enhancing the wear resistance. Moreover, the friction and wear coefficients, as well as the wear rates, decreased with the increasing cladding speed. The wear mechanism of the coatings was a combination of abrasive and adhesive wear. The refinement of the grain size and the increased grain boundary density due to the increasing cladding speed enhance the wear resistance of the coating. |
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