| YANG Guang-feng,GAO Feng,CUI Jing.Effect of Laser Power on Microstructure and Properties of TC4 Coated Coating[J],52(1):346-353 |
| Effect of Laser Power on Microstructure and Properties of TC4 Coated Coating |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.01.035 |
| KeyWord:TC4 ultrafast laser laser power laser cladding microstructure |
| Author | Institution |
| YANG Guang-feng |
School of Aviation Engineering,Tianjin , China |
| GAO Feng |
School of Transportation Science and Engineering, Civil Aviation University of China, Tianjin , China |
| CUI Jing |
School of Aviation Engineering,Tianjin , China |
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| Abstract: |
| It is an advanced surface modification technology. TC4 composite coating prepared by laser cladding can improve the surface properties without changing the matrix material, such as wear resistance, corrosion resistance, oxidation resistance, microhardness and other properties. The TC4 coated TC4 powder has good compatibility, small parameter differences, and the interface between the substrate and the molten powder is stronger, so the molten powder selects the TC4 powder. In this paper, we study the influence of the power parameters on the organization of the TC4 molten TC4 powder and its performance. The power parameters of the best performance coating are obtained, aiming to provide a reference for the laser power parameters in the aero-engine shell repair work. Use TC4 steel strip as substrate, polish and clean with sand paper. TC4 powder is precoated on clean TC4 steel. Ldm-8060 ultra-fast laser was used in the experiment. The scanning speed was uniformly limited to 100 mm/min, and three sets of power were set:1 000 W, 1 500 W and 2 000 W. Cut the sample with wire cutting and polish the cross section, and corrode it with Kroll solution. Then, observe the microstructure of the cladding layer by metallographic microscope (LEICA MEF4) and a scanning electron microscope (HITACHIS-3400N). Then use an energy spectrometer to perform EDS spectrum analysis on both sides of the bond line. Analyze the phase composition of the coating by an X-ray diffractometer (D/MAX-2500X) and test the microhardness of the cladding layer and matrix by microhardness tester (HVS-1000). The friction test was carried out on MPX-3G pin-disc friction and wear test machine, and the wear weight loss of the specimen was calculated, and the probe wear mark measuring instrument (MP-05) was used to measure the wear weight parameter of wear mark after friction. The composite coating on TC4 steel was successfully prepared by laser cladding technology. The optimal power parameter is 1 500 W. The cladding quality of the specimen is affected by power parameters. Low power will lead to shallower cladding layer, while high power will lead to damage of matrix due to over burning. Under the three power parameters, the tissues were mainly composed of fine granular cellular crystals, fine needle-like dendritic crystals and coarse dendritic crystals, respectively. With the increase of power, the number and density of tissues gradually decreased, and the development direction became more regular. The laser power has little effect on the changes of elements in the cladding layer, and TiN, Ti2N and other hard phases are formed. The hardness and wear resistance of the coating are significantly enhanced, and the hardness is up to 840.5HV. In the power range of 1 000-2 000 W, the wear property increases first and then decreases. Under the power of 1 500 W, the lowest wear is only 0.000 571 g, while under the power of 2 000 W, the wear property is lower than the matrix due to the high power. At the same time, the coating has the highest corrosion potential and the lowest corrosion current density under the power of 1 500 W, and the corrosion resistance is the strongest. To sum up, appropriate scanning power parameters have the best cladding quality, hardness, corrosion resistance and wear resistance. |
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