scholarly journals Analysis of In Situ Optical Signals during Laser Metal Deposition of Aluminum Alloys

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 589
Author(s):  
Liqun Li ◽  
Xian Wang ◽  
Yichen Huang
Keyword(s):  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Real Time ◽  
Metal Deposition ◽  
Infrared Light ◽  
Laser Metal Deposition ◽  
Optical Signals ◽  
Thin Walled ◽  
Deposition Height

During laser metal deposition (LMD) of thin-walled aluminum alloy structures, the deposition height and width is hard to keep stable because of the special properties of aluminum alloys, such as high reflectivity to laser beams, low viscosity, and high thermal conductivity. Monitoring the LMD process allows for a better comprehension and control of this process. To investigate the characteristics of the aluminum alloy LMD process, three real-time coaxial optical sensors sensitive to visible light, infrared light, and back-reflected lasers ere used to monitor the aluminum alloy LMD process. Thin-walled parts were deposited with different laser power, and the characteristics of the three in situ signals are analyzed. The results show that there exists high linear correlation between reflected laser and accumulated deposition height. A laser reflection model was built to explain the correlation. Besides, the infrared light is linearly correlated with deposition width. Overall, the results of this study show that the optical signals are able to reflect the deposition height and width simultaneously. Infrared light signals and reflected laser signals have the potential to serve as the input of online feedback geometry control systems and real-time defect alarm systems of the LMD process.

Preliminary Experimental Study of Warm Ultrasonic Impact-assisted Laser Metal Deposition

2021 ◽  
pp. 1-15
Author(s):  
Hanyu Song ◽  
Minglang Li ◽  
Muxuan Wang ◽  
Benxin Wu ◽  
Ze Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Solid Material ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Ultrasonic Impact Treatment ◽  
Post Process ◽  
Underlying Mechanisms ◽  
Manufacturing Time

Abstract A preliminary experimental study on “warm ultrasonic impact-assisted laser metal deposition” (WUI-LMD) is reported, and such a study is rare in literatures to the authors' knowledge. In WUI-LMD, an ultrasonic impact treatment (UIT) tip is placed near laser spot for in-situ treatment of laser-deposited warm solid material, and the UIT and LMD processes proceed simultaneously. Under the conditions investigated, it is found that in-situ UIT during WUI-LMD can be much more effective in reducing porosity than a post-process UIT. Possible underlying mechanisms are analyzed. WUI-LMD has a great potential to reduce defects and improve mechanical properties without increasing manufacturing time.

scholarly journals In-situ Monitoring and Defect Detection for Laser Metal Deposition by Using Infrared Thermography

2016 ◽  
Vol 83 ◽  
pp. 1244-1252 ◽  
Author(s):  
Ulf Hassler ◽  
Daniel Gruber ◽  
Oliver Hentschel ◽  
Frank Sukowski ◽  
Tobias Grulich ◽  
...  
Keyword(s):  
Infrared Thermography ◽  
Defect Detection ◽  
Metal Deposition ◽  
In Situ Monitoring ◽  
Laser Metal Deposition

In-Process Laser Re-Melting of Thin Walled Parts to Improve Surface Quality after Laser Metal Deposition

2019 ◽  
Vol 813 ◽  
pp. 191-196
Author(s):  
Francesco Bruzzo ◽  
Guendalina Catalano ◽  
Ali Gökhan Demir ◽  
Barbara Previtali
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Surface Quality ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Average Roughness ◽  
Thin Walls ◽  
Energy Inputs ◽  
Thin Walled

Laser metal deposition (LMD) is an additive manufacturing process highly adaptable to medium to large sized components with bulky structures as well as thin walls. Low surface quality of as-deposited LMD manufactured components with average roughness values (Ra) around 15-20μm is one of the main drawbacks that prevent the use of the part without the implementation of costly and time-consuming post-processes. In this work laser re-melting is applied right after LMD process with the use of the same equipment used for the deposition to treat AISI 316L thin walled parts. The surface quality improvement is assessed through the measurement of both areal surface roughness Sa(0.8mm) QUOTE and waviness Wa QUOTE (0.8mm) parameters. Moreover, roughness power spectrum is used to point out the presence of principal periodical components both in the as-deposited and in the re-melted surfaces. Then, the transfer function is calculated to better understand the effects of laser re-melting on the topography evolution, measuring the changes of individual components contributing to the surface roughness such as the layering technique and the presence of sintered particles. Experiments showed that while low energy density inputs are not capable to properly modify the additive surface topography, excessive energy inputs impose a strong periodical component with wavelength equal to the laser scan spacing and directionality determined by the used strategy. When a proper amount of energy density input is used, laser re-melting is capable to generate smooth isotropic topographies without visible periodical surface structures.

Research of Closed-Loop Control of Deposition Height in Laser Metal Deposition

2017 ◽  
Vol 44 (7) ◽  
pp. 0702004 ◽  
Author(s):  
石拓 Shi Tuo ◽  
卢秉恒 Lu Bingheng ◽  
魏正英 Wei Zhengying ◽  
周亮 Zhou Liang ◽  
石世宏 Shi Shihong
Keyword(s):  
Closed Loop ◽  
Metal Deposition ◽  
Closed Loop Control ◽  
Laser Metal Deposition ◽  
Loop Control ◽  
Deposition Height

scholarly journals Fabrication of Metal Matrix Composite by Laser Metal Deposition—A New Process Approach by Direct Dry Injection of Nanopowders

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3584 ◽  
Author(s):  
Briac Lanfant ◽  
Florian Bär ◽  
Antaryami Mohanta ◽  
Marc Leparoux
Keyword(s):  
Metal Matrix ◽  
Metallic Matrix ◽  
Process Approach ◽  
Metal Deposition ◽  
Al2o3 Nanoparticles ◽  
Laser Metal Deposition ◽  
Metal Matrix Nanocomposites ◽  
X Ray ◽  
New Process

Laser Metal Deposition (LMD) offers new perspectives for the fabrication of metal matrix nanocomposites (MMnCs). Current methods to produce MMnCs by LMD systematically involve the premixing of the nanopowders and the micropowders or require in-situ strategies, thereby restricting the possibilities to adjust the nature, content and location of the nano-reinforcement during printing. The objective of this study is to overcome such restrictions and propose a new process approach by direct injection of nanoparticles into a metallic matrix. Alumina (n-Al2O3) nanoparticles were introduced into a titanium matrix by using two different direct dry injection modes in order to locally increase the hardness. Energy dispersive X-ray spectroscopy (EDS) analyses validate the successful incorporation of the n-Al2O3 at chosen locations. Optical and high resolution transmission electron microscopic (HR-TEM) observations as well as X-ray diffraction (XRD) analyses indicate that n-Al2O3 powders are partly or totally dissolved into the Ti melted pool leading to the in-situ formation of a composite consisting of fine α2 lamellar microstructure within a Ti matrix and a solid solution with oxygen. Mechanical tests show a significant increase in hardness with the increase of injected n-Al2O3 amount. A maximum of 620 HV was measured that is almost 4 times higher than the pure LMD-printed Ti structure.

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