| LIU Guang,SHI Tuo,FU Ge-yan,WU Jie,YANG Qiang,WEI Chao,LI Kuan,LI Jian-bin.#$NP Numerical Simulation of Temperature Field and Process Research of Wide- band Cladding with Dual Linear Laser by Inside-laser Powder Feeding[J],52(5):322-335 |
| #$NP Numerical Simulation of Temperature Field and Process Research of Wide- band Cladding with Dual Linear Laser by Inside-laser Powder Feeding |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.05.032 |
| KeyWord::Anodic Oxidation of U02. Part 1. Electrochemical and X-Ray Photoelectron Spectroscopic Studies in Neutral Solutions[J]. Chemischer Informationsdienst, 1982, 13(12):198212014. |
| Author | Institution |
| LIU Guang |
School of Mechanical and Electric Engineering,Jiangsu Suzhou , China |
| SHI Tuo |
School of Optoelectronic Science and Engineering, Soochow University, Jiangsu Suzhou , China |
| FU Ge-yan |
School of Mechanical and Electric Engineering,Jiangsu Suzhou , China |
| WU Jie |
School of Mechanical and Electric Engineering,Jiangsu Suzhou , China |
| YANG Qiang |
Aviation Key Laboratory of Science and Technology on Structures Impact Dynamics, Aircraft Strength Research Institute of China, Xi'an , China |
| WEI Chao |
School of Mechanical and Electric Engineering,Jiangsu Suzhou , China |
| LI Kuan |
School of Mechanical and Electric Engineering,Jiangsu Suzhou , China |
| LI Jian-bin |
School of Mechanical and Electric Engineering,Jiangsu Suzhou , China |
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| Abstract: |
| As a surface engineering technology with great application potential, laser cladding technology has been widely used in the strengthening of important metal parts in aerospace, oil exploration, coal mining and other fields, which has become one of the mainstream surface functional coating preparation technologies. However, the spot size of the traditional laser cladding nozzle is too small, which affects the preparation efficiency of the coating and causes too many overlap defects in the large-area cladding. Compared with the traditional circular spot size, the existing laser wide-band cladding technology has been greatly improved, but the quality of coating preparation and powder utilization still have a lot of room for improvement. In order to change this situation, a high-power and coaxial inside-laser powder feeding wide-band cladding nozzle has been independently developed. The work aims to conduct experimental research on the temperature field distribution characteristics and the effect of process parameters on the morphology and geometric characteristics of the cladding layer based on the nozzle and provide technical reference for traditional surface modification technologies such as electroplating and thermal spraying with high pollution, high cost, low efficiency and poor bonding. Based on the parametric design language of ANSYS software, the semi-ellipsoid heat source model was selected to establish the laser cladding model with continuous moving loading of dual linear spot. The whole cladding process was simulated by the life-death element method to explore the temperature distribution characteristics of the cladding layer. The simulation results showed that the temperature distribution of laser wide-band single channel cladding process changed from "linear spot" to "banded comet" gradually, and the isotherms in front of the molten pool were dense and the temperature gradient was large. At the defocusing amount of 0 mm, the area with the highest temperature of the molten pool coincided with the loading position of the heat source. In the negative defocus state, the area with the highest molten pool temperature was located at the second spot of the dual linear spot. Whether in the state of 0 mm defocusing amount or negative defocus, the high- temperature area on the cross section of the cladding layer presented a "flat bottom" distribution, while the high-temperature area on the longitudinal section presented a "V" shape and an asymmetric "W" shape respectively, which gradually transitioned to a "semi elliptical" shape with the increase of depth. The fixed-point temperature of cladding process was measured by infrared thermometer, which verified the rationality of the model established. The effects of defocusing amount, powder feeding speed, laser power and scanning speed on the morphology and geometric characteristics of cladding layer were studied by single-factor basic process experiments and the optimal process parameters were determined as follows:defocusing amount of ‒3-0 mm, powder feeding speed of 27-45 g/min, scanning speed of 1.5-3 mm/s and laser power of 5.4-6 kW. The results show that KF-355 metal powder is melted on 304 stainless steel. The "banded comet" temperature distribution of single cladding channel makes the temperature gradient in front of the molten pool larger and the temperature gradient behind smaller. The "flat bottom" temperature distribution on the cross section can strengthen the bonding degree between the cladding layer and the substrate in the width direction. When the cladding experiment is carried out with the process parameters of defocusing amount of 0 mm, powder feeding rate of 45 g/min, laser power of 6 kW and scanning speed of 3 mm/s, the cladding layer with smooth surface and no obvious defects such as cracks and holes can be obtained. The width, thickness, surface smoothness, dilution rate and cladding efficiency of the cladding layer are 39.713 mm, 0.732 mm, 0.121 mm, 0.073 and 0.43 m2/h based on the above process parameters, respectively. The average hardness of the coating area is 645.6HV0.5, which is 3.35 times higher than the average hardness of the substrate (192.9HV0.5). |
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