scholarly journals Evaluation of the quality of layers applied by LDT laser metal deposition

2018 ◽  
Vol 19 (6) ◽  
pp. 591-596
Author(s):  
Andrzej Mazurkiewicz ◽  
Andrzej Poprzeczka
Keyword(s):  
Heat Affected Zone ◽  
Heat Dissipation ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Cross Sectional ◽  
Weld Overlay ◽  
The Cross

The article presents the results of a study of C45 carbon steel hardfacing using laser metal deposition with Stellit Co-21 powder. The microstructure of the cross-section of samples prepared with different scanning speed and the amount of used powder at constant laser power was observed. Analyzing the cross-sectional areas of the samples, it was found that, at specific production parameters, cracks occur in weld overlay, which should be associated with the amount of heat supplied and discharged, especially at the unheated basis.This may be confirmed by the presence of deposits of weakly branched dendrites in the microstructure, which should be related to the directional heat dissipation process and rapid directional crystallization. It is possible to regulate these phenomena by selecting appropriate processing parameters. The microstructure analysis of cross-sectional areas of samples after hardfacing using LDT technique indicates good metallurgical quality of the deposit with a small heat affected zone of about 660÷760m. The microhardness measurements on the sample cross-sections indicated a wide micohardness distribution ranging from 510HV1 in the weld overlay, about 410HV1 in the heat affected zone, to 270HV1 in the C45 steel base.

Influences of Processing Parameters on Dilution Ratio of Laser Cladding Layer during Laser Metal Deposition Shaping

2012 ◽  
Vol 549 ◽  
pp. 785-789 ◽  
Author(s):  
Kai Zhang ◽  
Xin Min Zhang ◽  
Wei Jun Liu
Keyword(s):  
Laser Cladding ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Dilution Ratio ◽  
Factors Affecting ◽  
Cladding Layer ◽  
Performance Quality ◽  
And Performance

Laser Metal Deposition Shaping (LMDS) is a state-of-the-art technology that combines rapid prototyping and laser processing. There are many factors affecting the quality, precision, microstructure and performance of LMDS-deposited parts. Among them, dilution ratio is a significant one since it is not only an important index to judge the laser cladding quality, but directly affects the interlayer bonding strength and performance quality of as-formed metal parts. Thus, the substantial LMDS experiments were performed to conclude the influence of processing parameters on dilution ratio of laser cladding layer. The results indicate that the influence degree of scanning speed is most significant, while that of laser power is relatively slight. In order to ensure the perfect forming quality and strong metallurgical bonding, it is necessary to choose suitable dilution ratio to accomplish the LMDS process.

Integration of pure copper to optimize heat dissipation in injection mould inserts using laser metal deposition

2021 ◽  
Vol 33 (1) ◽  
pp. 012029
Author(s):  
Stefan Polenz ◽  
Christian Kolbe ◽  
Florian Bittner ◽  
Elena López ◽  
Frank Brückner ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Pure Copper ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Injection Mould

Formation of the Cast Iron Coatings Plasma-Sprayed at Different Substrate Temperatures

2010 ◽  
Vol 44-47 ◽  
pp. 2144-2147
Author(s):  
Ya Zhe Xing ◽  
Chao Ping Jiang ◽  
Hong Chen ◽  
Jian Min Hao
Keyword(s):  
Cast Iron ◽  
Substrate Temperature ◽  
Phase Structure ◽  
Processing Parameters ◽  
Optical Microscope ◽  
Atmospheric Plasma ◽  
Cross Sectional ◽  
The Cross ◽  
Plasma Sprayed ◽  
Iron Coatings

In this work, three cast iron coatings were produced by atmospheric plasma spraying. During spraying, the surface temperature of three coatings (substrate temperature) was controlled to be averagely 50oC, 180oC and 240oC by changing the processing parameters. X-ray diffraction (XRD) was employed to analyze the phase structure of the starting powder and the coatings. The results showed that the powder was mainly composed of (Fe,Cr)7C3 and martensite and both the spraying processing and the substrate temperature exerted no influence on coating phase structure. An optical microscope (OM) was used to characterize the microstructure of the cross-section and surface of the coatings. It was found that the cross sectional hardness increased with the increase of the substrate temperature due to the improvement in interlamellar bonding.

Effect of Laser Processing Parameters on Microhole Quality of Aluminium Nitride Ceramics

2021 ◽  
Vol 871 ◽  
pp. 277-283
Author(s):  
Chun Yan Yang ◽  
Yun Hao ◽  
Bozhe Wang ◽  
Hai Yuan ◽  
Liu Hui Li
Keyword(s):  
Laser Processing ◽  
Laser Power ◽  
Picosecond Laser ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Recast Layer ◽  
Aluminium Nitride ◽  
Obvious Effect ◽  
Nitride Ceramics

A picosecond laser in spin-cutting mode was used to drill 500μm diameter microholes on 150μm thick aluminium nitride ceramic. The effects of laser processing parameters such as the laser power, scanning speed, and defocus amount on the microhole quality were studied. The results show that as the laser power increases, the inlet and outlet diameters of the holes increase, the taper decreases slightly, and the thickness of the recast layer decreases evidently. The scanning speed has no obvious effect on the diameter and taper of the hole; however, the hole can not be drilled through when the speed is too large. Positive defocus can effectively reduce the taper of the hole. Under 28.5W laser power, 400Hz frequency, 200mm/s scanning speed, and zero defocus amount conditions, high-quality microholes with a taper of 0.85° were obtained.

Cladding of Stellite-6/WC Composites Coatings by Laser Metal Deposition

2018 ◽  
Vol 941 ◽  
pp. 1645-1650 ◽  
Author(s):  
Takahiro Kunimine ◽  
Ryusei Miyazaki ◽  
Yorihiro Yamashita ◽  
Yoshinori Funada ◽  
Yuji Sato ◽  
...  
Keyword(s):  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Metal Deposition ◽  
Matrix Composites ◽  
Laser Metal Deposition ◽  
Feeding Rates ◽  
Coating Materials ◽  
Cross Sectional ◽  
Stellite 6 ◽  
Powder Feeding

This study aims to investigate the microstructure and hardness of multi-layered Stellite-6/WC metal-matrix composites coatings on metallic substrates cladded by laser metal deposition (LMD) for improvement of wear and corrosion resistances. As coating materials, Stellite-6 and WC-12wt.%Co powders were selected. Powder mixtures having various mixing-ratios of Stellite-6 and WC-12wt.%Co were provided vertically on S45C substrates by controlling powder feeding rates of the two powder feeders, individually. Stellite-6/WC composites which consist of three layers with different compositions were cladded on the S45C substrates by laser melting. Cross-sectional microstructure observation was carried out by using an optical microscope (OM). Vickers microhardness tests were conducted to evaluate hardness of the cladding layers and substrates. The experimental results demonstrate that hard multi-layered Stellite-6/WC metal-matrix composites coatings were successfully cladded on the S45C substrates. Property gradients in the Stellite-6/WC composites could be made due to the position-dependent chemical composition and microstructure made by controlling powder feeding rates of an LMD system.

scholarly journals Ultrasonic-Assisted Laser Metal Deposition of the Al 4047Alloy

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1111 ◽  
Author(s):  
Zhang ◽  
Guo ◽  
Chen ◽  
Kang ◽  
Cao ◽  
...  
Keyword(s):  
Relative Density ◽  
Laser Power ◽  
Tensile Ductility ◽  
Processing Parameters ◽  
Metal Deposition ◽  
Ultrasonic Power ◽  
Laser Metal Deposition ◽  
Ultrasonic Assisted ◽  
Cast Alloys ◽  
Cast Parts

Ultrasonic-assisted laser metal deposition(UALMD) technology was used to fabricate Al 4047 parts. The effect of the powder feeding laser power, remelting laser power and ultrasonic power on the relative density of the parts was investigated. The relative density, microstructure and mechanical properties of the specimens obtained by the optimized process parameters were compared with the corresponding properties of the cast alloys. The results showed that dense alloys with a maximum density of 99.1% were prepared using ultrasonic vibration and by remelting the previously deposited layer with the optimized processing parameters, and its density was almost equivalent to that of the cast parts. The microstructure of the samples using optimal laser parameters presented columnar Al dendrites and equiaxed Si particles at the boundary of each deposited layer, while the supersaturated Al solid solution was transformed into equiaxed crystal surrounded by fine fibrous Si phases at the center of the layer. Moreover, the size of the primary Al and the Si particles in the samples produced by UALMD was remarkably refined compared to that of the primary Al and Si particles in the cast structure, resulting in grain refining strengthening. The observed variation in the microstructure had an obvious impact on the tensile properties. The mechanical behavior of the deposit obtained by UALMD revealed superior tensile strength, yield strength and tensile ductility values of 227 ± 3 MPa, 107 ± 4 MPa and 12.2 ± 1.4%, which were approximately 51%, 38% and 56% higher than those of the cast materials, respectively.

Elimination of Clogging in PMMA Microchannels Using Water Assisted CO2 Laser Micromachining

2015 ◽  
Vol 799-800 ◽  
pp. 407-412 ◽  
Author(s):  
Mohamed O. Helmy ◽  
Ahmed M. Fath El-Bab ◽  
Hassan El-Hofy
Keyword(s):  
Thin Layer ◽  
Heat Affected Zone ◽  
Scanning Speed ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Water Cooling ◽  
Quick Method ◽  
Lab On Chip ◽  
On Chip

The accuracy and clogging of microchannels are important for assessing the quality of lab on chip (L-O-C) devices. The clogging affects the fluid mixing efficiency and influences the bonding of substrate. In this paper, inexpensive and quick method for microchannel fabrication in polymethyl methacrylate (PMMA) while reducing the thermal damage is introduced. Accordingly, the substrate was covered with a thin layer of water during CO2laser ablation. The effect of water cooling on the clogging formation, heat affected zone and the microchannel geometry in terms of depth and width is investigated. Clogging formation mechanism in the intersection of Y-channel is studied to improve its quality for microfluidics applications. During the experimental work, the CO2laser power was varied from 2.4 to 6 W at scanning speed from 5 to 12.5 mm/s. The results showed that covering the PMMA substrate with a thin layer of water prevented clogging formation and reduced the heat affected zone.

Research on Cladding Nickel on Copper Crystallizer Using Laser Metal Deposition Technique

2010 ◽  
Vol 97-101 ◽  
pp. 3846-3851 ◽  
Author(s):  
Guang Yang ◽  
Wei Jun Liu ◽  
Wei Wang ◽  
Fei Xing ◽  
Feng Jie Tian ◽  
...  
Keyword(s):  
Erosion Resistance ◽  
Energy Dispersive Spectrometer ◽  
Processing Parameters ◽  
Metal Deposition ◽  
Bonding Interface ◽  
Laser Metal Deposition ◽  
Optimal Processing ◽  
Large Numbers ◽  
Nickel Based Alloy ◽  
Cladding Layers

To increase the strength and erosion resistance of Copper Crystallizer, the system based on Laser Metal Deposition (LMD) process was proposed to clad nickel-based alloy on its surface. With the optimal processing parameters ascertained by large numbers of experiments, the crystallizer was clad nickel-based alloy. The morphology and the microstructures of the cladding layers and bonding interface were analyzed by energy dispersive spectrometer and scanning electronic microscopy. The result shows that the bonding interface realizes the metallurgic and tight bonding.

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.

Sign in / Sign up

Export Citation Format

Share Document