| WANG Yuhao,ZHOU Houming,WANG Zeda,XIANG Nanxin,CAO Xingyu.Effect of Electromagnetic Field on Microstructure Properties of Laser Cladding Nickel-based Coatings[J],53(21):198-207 |
| Effect of Electromagnetic Field on Microstructure Properties of Laser Cladding Nickel-based Coatings |
| Received:November 09, 2023 Revised:February 26, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.21.020 |
| KeyWord:laser cladding electromagnetic fields elemental segregation electromagnetic stirring coating performance |
| Author | Institution |
| WANG Yuhao |
School of Mechanical Engineering and Mechanics, Xiangtan University, Hunan Xiangtan , China |
| ZHOU Houming |
School of Mechanical Engineering and Mechanics, Xiangtan University, Hunan Xiangtan , China |
| WANG Zeda |
School of Mechanical Engineering and Mechanics, Xiangtan University, Hunan Xiangtan , China |
| XIANG Nanxin |
School of Mechanical Engineering and Mechanics, Xiangtan University, Hunan Xiangtan , China |
| CAO Xingyu |
School of Mechanical Engineering and Mechanics, Xiangtan University, Hunan Xiangtan , China |
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| Abstract: |
| Laser cladding technology is an environmentally friendly surface modification technology, which has the characteristics of high precision, small heat input, dense structure of prepared parts, etc. In this process, different kinds of metal powders can be covered by high power laser melting to the substrate surface to obtain different properties. It has great development potential in parts repair, surface strengthening and other aspects, but some scholars have found that in the process of laser cladding, due to the segregation of elements in the melt pool, the surface performance of the coating will be reduced and even defects such as cracks and pores will appear. The aim of this work is to study the effect of electromagnetic field on the microstructure and properties of the laser cladding Ni-based coating on 45 steel by adding an electromagnetic field to the laser cladding process. In the experiment, a steady-state magnetic field with a size of 80 mT and a downward direction was used. At the same time, alternating current and direct current of different sizes were applied to the 45 steel matrix during processing. The alternating current frequency was 5 Hz, and the current size was 100 A, 200 A, and 300 A, respectively. A coaxial laser cladding device (TFL-H6000) was used for multi-channel laser cladding, the bonding rate was 30%, the protective gas was Ar gas, and the laser cladding process parameters were selected as power 1 800 W, scanning speed 5 mm/s, and powder delivery capacity 4 g/s. Six samples were prepared. And after polishing, metallographic corrosion was carried out with mixed reagents (anhydrous ethanol, FeCl3, concentrated hydrochloric acid). A metallographic microscope (JSM-6360LV), a scanning electron microscope (JSM-6510LV), and an X-ray diffractometer (D/MAX-2500PC) were used to observe and analyze the microstructure, phases, and elements of the cladding layer. The friction and wear properties of the cladding layer were measured with a reciprocating friction and wear tester (HRS-2M), and electrochemical experiments were carried out on an electrochemical workstation. The stirring effect of the electromagnetic field on the melt pool would change the growth and distribution of the microstructure of the cladding layer and accelerate the heat and mass transfer of the cladding layer, thus reducing the formation of CrB, Ni2B and other substances and reducing the macro and micro segregation of the cladding layer. Among them, the segregation degree of the AC electric field (AC) sample group was lower than that of the DC sample group with the same current size. The AC200 sample had the least segregation, and the AC200 sample had the least wear amount and the best wear resistance in the friction and wear test. The self-corrosion potential of the coatings prepared with the aid of electromagnetic field was significantly higher than that of the non-electromagnetic field coating, and the current density was lower than that of the non-electromagnetic field coating. The AC200 sample had the highest self-corrosion potential of −185 mV and the lowest self-corrosion current density of 6.01 μA/cm2, and its corrosion resistance was the best for the whole group of samples. It is found that the corrosion resistance of coating increased first and then decreased with the increase of AC and DC current, and the performance of AC sample was better than that of DC sample with corresponding current. The electromagnetic field assisted laser cladding can significantly reduce the macro and micro segregation of the coating and improve the performance of the coating, and the coating prepared under AC200 conditions has the best performance. |
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