Effects of the gas flow and the defocusing distance from laser beam focus on powder-feed laser cladding

2010 ◽  
Author(s):  
Yuanyuan Li ◽  
Jichang Liu
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Seok-Ho Maeng ◽  
Hakju Lee ◽  
Min Soo Park ◽  
Suhyun Park ◽  
Jaeki Jeong ◽  
...  

AbstractWe report the extraction of silicon via a carbothermal reduction process using a CO2 laser beam as a heat source. The surface of a mixture of silica and carbon black powder became brown after laser beam irradiation for a few tens of seconds, and clear peaks of crystalline silicon were observed by Raman shift measurements, confirming the successful carbothermal reduction of silica. The influence of process parameters, including the laser beam intensity, radiation time, nitrogen gas flow in a reaction chamber, and the molar ratios of silica/carbon black of the mixture, on the carbothermal reduction process is explained in detail.


2012 ◽  
Vol 499 ◽  
pp. 114-119 ◽  
Author(s):  
Ming Di Wang ◽  
Shi Hong Shi ◽  
X.B. Liu ◽  
Cheng Fa Song ◽  
Li Ning Sun

Numerical simulation of laser cladding is the main research topics for many universities and academes, but all researchers used the Gaussian laser light source. Due to using inside-beam powder feeding for laser cladding, the laser is dispersed by the cone-shaped mirror, and then be focused by the annular mirror, the laser can be assumed as the light source of uniform intensity.In this paper,the temperature of powder during landing selected as the initial conditions, and adopting the life-and-death unit method, the moving point heat source and the uniform heat source are realized. In the thickness direction, using the small melt layer stacking method, a finite element model has been established, and layer unit is acted layer by layer, then a virtual reality laser cladding manu-facturing process is simulated. Calculated results show that the surface temperature of the cladding layer depends on the laser scanning speed, powder feed rate, defocus distance. As cladding layers increases, due to the heat conduction into the base too late, bath temperature will gradually increase. The highest temperature is not at the laser beam, but at the later point of the laser beam. In the clad-ding process, the temperature cooling rate of the cladding layer in high temperature section is great, and in the low-temperature, cooling rate is relatively small. These conclusions are also similar with the normal laser cladding. Finally, some experiments validate the simulation results. The trends of simulating temperature are fit to the actual temperature, and the temperature gradient can also ex-plain the actual shape of cross-section.


2021 ◽  
Vol 11 (07) ◽  
pp. 121-130
Author(s):  
V. N. Demin ◽  
V. O. Borisov ◽  
G. N. Grachev ◽  
A. L. Smirnov ◽  
M. N. Khomyakov ◽  
...  

2014 ◽  
Vol 41 (7) ◽  
pp. 0703012
Author(s):  
吴东江 Wu Dongjiang ◽  
褚洋 Chu Yang ◽  
牛方勇 Niu Fangyong ◽  
马广义 Ma Guangyi ◽  
庄娟 Zhuang Juan

2004 ◽  
Vol 120 ◽  
pp. 405-412
Author(s):  
J. Ahlström ◽  
B. Karlsson ◽  
S. Niederhauser

A model on laser cladding of medium carbon steel, used in railway wheels and rails, is developed and implemented. When the laser beam is scanned over the surface during the cladding operation, phase transformations occur in the topmost layer of the substrate material due to rapid heating and cooling. The hardened regions may later be annealed, either during subsequent passes of the laser beam or by for example induction heating. The current model is a first step towards judging the resulting microstructure and hardness in the heat affected zone under the clad.


2008 ◽  
Vol 375-376 ◽  
pp. 338-342 ◽  
Author(s):  
Xia Ji ◽  
Jian Zhong Zhou ◽  
Hua Feng Guo ◽  
Da Peng Xu

This paper presents an experimental investigation on the metal components fabricated by laser cladding. In the present study, two process of laser cladding were conducted, that is pre-placed powder cladding and coaxial powder-feed cladding. The effect of processing parameters was studied and optimum set of parameters for the superior surface quality was established by employing the orthogonal design. The fabricated components were subjected to metallographic examinations and micro-hardness measurement. Results indicated that the microstructure of coaxial cladding components was finer than pre-placed powder cladding components. The micro-hardness of the fabricated specimen along and vertical the scanning direction were measured using a HVS-1000 micro-hardness tester with a 200 g applied load. Analysis of the physical properties provided further evidence of differences in micro-hardness produced by different process conditions, and the average micro-hardness value of pre-placed power cladding layer was lower than the coaxial powder-feed cladding layer.


2010 ◽  
Vol 29-32 ◽  
pp. 571-576
Author(s):  
Lie Chen ◽  
Pei Lin Xie

Temperature field of laser cladding on teeth surfaces of gear shaft was numerical simulated with finite element analysis software – ANSYS. The simulation result show that the heat caused by laser beam is concentrated inside the tooth mostly. An effect of preheating in the adjacent tooth is also brought about by injected laser energy. In order to make use of the effect of preheating and avoid the concentration of heat, all of the corresponding flanks of teeth should be cladded first and the other flanks of teeth be cladded secondly in the process of laser cladding. It is also shown that the problems of excessive melted down and collapsing of tooth-tip would be easily resulted in by the heat that concentrated in tooth-tip if the tooth-side and tooth-tip be cladded at the same time. The results of analysis and experiment show that at least two times of scanning should be executed in the process of laser cladding on teeth surfaces. At the first scanning, dimension of laser beam should be reduced properly. And the tooth-tip should not be irradiated directly by laser beam. After the first scanning, the gear should be circumrotated a certain angle. And the included angles between the two sides of tooth-tip and horizontal plane should be approximately equal. Then the second scanning could be prosecuted at the tooth-tip. Experiment results show that continuous and compact cladding coat could be gained by this craft. It is proved that this technological craft is reasonable and effective.


2018 ◽  
Author(s):  
Mingsan Xu ◽  
Kerstern Malama ◽  
Bingbing Li

Laser cladding utilizes a high-powered laser to fuse and solidify the metal powders, which results in a complex change of physical and mechanical properties. Selection of parameters and creative structure design are critical for laser cladding technology. High-speed steel is cladded on the base metal 40Cr by diode laser to investigate the influence of curvature radius, scanning speed, gas flow and laser power. The micro hardness and residue stress are tested while the microstructure is analyzed. According to analysis of the process parameters in orthogonal experiment, the optimal parameters are: curvature radius 100 mm, laser power 1200W, gas flow 1000 L/h, and scanning speed 16 mm/s. Under the optimal parameters, the microstructure and grid is uniform and the grain growth is along the same direction.


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