Laser Re-Melt Technique for Laser Additive Repair of Narrow Rectangular Cracks in Grade 5 Titanium Alloy (Ti-6Al-4V)

2019 ◽  
Vol 796 ◽  
pp. 129-136
Author(s):  
Tawanda Marazani ◽  
Daniel Makundwaneyi Madyira ◽  
Esther Titilayo Akinlabi
Keyword(s):  
Gas Flow ◽  
Focal Length ◽  
Scanning Speed ◽  
Spot Size ◽  
Additive Technology ◽  
Rectangular Crack ◽  
Grade 5 ◽  
Crack Repair ◽  
Repair Attempts ◽  
Size Powder

Groove inaccessibility, top groove powder impedance, irregular sidewall powder delivery and lack of sidewall vertical irradiation have been reported as major limitations for the use of Laser Additive Technology (LAT) for narrow rectangular crack repair applications. As a result, most reported repair attempts were concluded unsuccessful. In the present work, a multi-track laser re-melt technique was developed for the repair of narrow rectangular cracks of sizes 2 and 3 mm, both 5 mm deep on 7 mm thick Ti-6Al-4V plates. The laser re-melt technique was carried out at controlled laser power, focal length, spot size, powder feed rate, gas flow rate and scanning speed. The repaired substrates were evaluated for defects through optical microscopy (OM) and scanning electron microscopy (SEM). The obtained results showed densely fused defect-free repaired substrates with good evolving microstructure.

Microstructural Enhancement and Performance of Additive Manufactured Titanium Alloy Grade 5 Composite Coatings

2020 ◽  
Author(s):  
O. S. Fatoba ◽  
S. A. Akinlabi ◽  
E. T. Akinlabi ◽  
L. C. Naidoo ◽  
A. A. Adediran ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Laser Scanning ◽  
Gas Flow ◽  
Composite Coatings ◽  
Laser System ◽  
Scanning Speed ◽  
Deposition Process ◽  
Traverse Speed ◽  
Industrial Applications ◽  
Grade 5

Abstract The surface integrity of Titanium alloy may be improved by surface modification, to expand its availability for more diverse industrial applications. Additive manufacturing is a commercially competitive manufacturing technique with the possibility of altering the entire perception of design and fabrication. The study experimentally investigates the effects that Ytterbium Laser System process parameters, such as laser power, powder feed rate and traverse speed, has on the resultant microstructure of Ti-6Al-4V grade 5 alloy. The deposition process was conducted employing a 3kW (CW) Ytterbium Laser System (YLS-2000-TR) machine, coaxial to the reinforcement powder. The laser scanning speed and power were varied between the intervals of 1–1.2 m/min and 900–1000 W. All other parameters kept constant were the rate of gas flow, the spot diameter, and the rate of powder flow. The microstructure was characterized by grain size and morphology by using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). During the DLMD process, the thermal histories induced in the process led to the promotion of the transformed α+β microstructure from the initial primary a microstructure; the growth and evolution of the distinct grain morphologies and stability of the alpha and beta structures upon increased and reduced structures. It was ascertained that by increasing the traverse speeds, the cooling rates increased, which resulted in the decrease in the width of the columnar grains.

The Influence of GGG70L Laser Surface Hardening Power on Quenched Layer Performance

2013 ◽  
Vol 774-776 ◽  
pp. 1051-1054
Author(s):  
Yun Tao Li ◽  
Fei Xiang Jin ◽  
Ning Xu Wang ◽  
Qing Chang ◽  
De Yu Liu
Keyword(s):  
Laser Scanning ◽  
Focal Length ◽  
Scanning Speed ◽  
Quality Standard ◽  
Spot Size ◽  
Laser Surface ◽  
Production Factors ◽  
Laser Scanning Speed ◽  
Die Material ◽  
Hardening Power

GGG70L die material laser phase change hardening aims to discover the Quenched Layer performance of the GGG70L die material hardened by the laser of different power. Making comparison and analysis in the experiment and considering the actual production factors such as cost, working efficiency and product quality standard, it is concluded that laser power being 1900 w, laser scanning speed 6mm/s, spot size 3×15 mm2, focal length being 305mm, the surface of the material quality can meet the requirements of industrial production, laser surface quenched layer becomes harder, good abrasion resistance on the surface of the material is obtained.

scholarly journals Influence of Rapid Solidification and Optimized Process Parameters on the Microstructural Evolution of Additive Manufactured Titanium Alloy Grade 5 Composite

2021 ◽  
Vol 309 ◽  
pp. 01147
Author(s):  
O.S. Fatoba ◽  
S.A. Akinlabi ◽  
O.M. Ikumapayi ◽  
E.T. Akinlabi
Keyword(s):  
Process Parameters ◽  
Laser Scanning ◽  
Gas Flow ◽  
Laser System ◽  
Scanning Speed ◽  
Deposition Process ◽  
Cooling Rates ◽  
Grade 5 ◽  
Direct Laser ◽  
Columnar Grains

The study experimentally investigates the effects that Ytterbium Laser System process parameters, such as laser power, powder feed rate and traverse speed, has on the resultant microstructure of Ti- 6Al-4V grade 5 alloy. The deposition process was conducted employing a 3kW (CW) Ytterbium Laser System (YLS-2000-TR) machine, coaxial to the reinforcement powder. The laser scanning speed and power were varied between the intervals of 1-1.2 m/min and 900-1000 W. All other parameters kept constant where the rate of gas flow, the spot diameter, and the rate of powder flow. The microstructure was characterized by grain size and morphology by using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The microstructural and mechanical properties were ascertained and the relationships with the process parameters were achieved. As a result of rapid cooling, the morphological features of α and α’ are distinctive and appear acicular. The structures appear coarsened. The metallurgy of the samples identifies with a morphology of multi-scale; with the coarsened alpha structures being reduced, plate-like, discrete and finer. The alpha grains closer to the fusion zone grew epitaxially, and the ones above these are acicular and lamellar. The results also indicated that slow traverse speeds increase the scale of columnar grains, while other process parameters were kept constant. Columnar microstructures became prevalent due to the dynamic temperature gradients/spikes, and sustainable cooling rates, pertaining to fabricating direct laser deposited Ti-6Al-4V grade 5 alloy. It was ascertained that by increasing the traverse speeds, the cooling rates increased, which resulted in a decrease in the width of the columnar grains.

INFLUENCE OF CEO2 ADDITION AND SCANNING SPEED ON MICROSTRUCTURE AND TRIBOLOGICAL BEHAVIOR OF LASER-CLAD Ti-Co REINFORCED COATINGS ON Ti-6Al-4V ALLOY

2019 ◽  
Vol 27 (04) ◽  
pp. 1950129
Author(s):  
O. S. ADESINA ◽  
G. A. FAROTADE ◽  
A. P. I. POPOOLA ◽  
D. T. OLORUNTOBA
Keyword(s):  
Gas Flow ◽  
Tribological Behavior ◽  
Surface Hardness ◽  
Wear Test ◽  
Rare Earth Oxide ◽  
Scanning Speed ◽  
Spot Size ◽  
Melt Pool ◽  
Scan Speed ◽  
Set Up

Ti-6Al-4V alloy is restricted in industrial application as a result of its relatively low hardness and poor tribological properties. However, the limitations associated with Ti-6Al-4V in severe tribological conditions can be improved via laser cladding technique. In this study, the influence of rare earth oxide (CeO[Formula: see text] addition on microstructure, hardness and tribological behavior of laser-clad titanium–cobalt-based coatings on Ti6Al4V alloy was investigated. The optimized parameters used for laser depositions are laser power 900[Formula: see text]W; beam spot size 3[Formula: see text]mm; powder feed rate 1.0[Formula: see text]g/min; gas flow rate 1.2[Formula: see text]L/min while laser scan speed was varied at 0.6[Formula: see text]m/min and 1.2[Formula: see text]m/min. Thereafter, the coating morphology as well as wear mechanism of the coatings of CeO2 particles (5–10[Formula: see text]wt.%) dispersed in TiCo matrix were investigated via scanning electron microscope (SEM) equipped with energy dispersed spectrometry (EDS), whereas the intermetallic phases present in the coatings were observed using Philips PW1713 X-ray diffractometer (XRD). Furthermore, the micro-hardness values of the coatings were recorded while wear test was carried out using a reciprocating set up (UMT-2 — CETR tribometer). Results revealed that the incorporation of CeO2 particles into the melt pool influenced the morphology of the coatings, thus resulting in finer cellular dendrites, homogenous and strong metallurgical bonding between the laser cladded coating and the substrate. The phases revealed various fractions of interdendritic compounds (CeCo2, Ni3Ti, Co2Ti, CoTi, Al2O3, TiO, AlTi3, and Ce2O[Formula: see text] dispersed within the coating matrix, thus resulting in 2.68 times improvement on the surface hardness and 47.4% reduction in friction coefficient in comparison with Ti-6Al-4V alloy.

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

Spot size and effective focal length measurements for a fast axial flow CO2 laser

1997 ◽  
Author(s):  
Robert J. Steele ◽  
Phillip W. Fuerschbach ◽  
Danny O. MacCallum
Keyword(s):  
Co2 Laser ◽  
Focal Length ◽  
Axial Flow ◽  
Spot Size ◽  
Effective Focal Length ◽  
Length Measurements

Applications of a novel detector for pencil beam scanning proton therapy beam quality assurance

2021 ◽  
pp. 2140041
Author(s):  
Pei-Ying Yang ◽  
Yang-Wei Hsieh ◽  
Chen-Lin Kang ◽  
Chin-Dar Tseng ◽  
Chih-Hsueh Lin ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Proton Therapy ◽  
Beam Quality ◽  
Beam Width ◽  
Scanning Speed ◽  
Spot Size ◽  
Pencil Beam ◽  
Beam Position ◽  
The Cross ◽  
One Year

This study utilized a new type of detector, the CROSS II (Liverage Biomedical Inc., Taiwan), to perform a beam quality assurance (QA) procedure on a Sumitomo (Sumitomo Heavy Industries, Inc., Japan) pencil beam linear scanning proton therapy machine. The Cross II can monitor proton Pristine Bragg peak range, beam width, beam size, beam position, and scanning speed. All the data presented here were collected during a time span of over one year. The accuracy of the QA program could be verified if all the QA items were tested stably and within the programmed tolerances. Our results showed that the proton range remained within the [Formula: see text] mm tolerance, with the majority of measurements within [Formula: see text] mm, [Formula: see text] mm for spot size, 1.5 mm for spot position, and [Formula: see text]% for scanning speed. We found that the CROSS II detector is in high precise and steady state with highly efficient. Our proton therapy system was also proven to be in an accurate and reliable condition according to our QA results.

scholarly journals EFFECT OF THE RUBY LASER MICROBEAM ON MITOCHONDRIA OF KB CELLS SUPRAVITALLY STAINED BY PINACYANOL

1969 ◽  
Vol 41 (2) ◽  
pp. 424-430 ◽  
Author(s):  
Yasukazu Tanaka
Keyword(s):  
Laser Beam ◽  
Ruby Laser ◽  
Focal Length ◽  
Direct Interaction ◽  
Experimental System ◽  
Spot Size ◽  
Kb Cells ◽  
Focal Spot Size ◽  
Laser Microbeam ◽  
Opaque Material

With pinacyanol as the supravital stain, a preferential effect on mitochondria of KB cells was achieved by the irradiation with the ruby laser beam. The observation confirmed the results of other workers using janus green B in the same experimental system. The preferential effect on mitochondria was noted in the area extending 8–10 µ beyond the nonpreferential damage of 4–5 µ in diameter. The opaque material associated with mitochondria possibly represented coagulated protein. The effect involved cristae mitochondriales without severe disarrangement of their structure. The opaque material could be interpreted as the result of direct interaction between mitochondria and the laser beam, even though the mitochondria were noted outside of the previously estimated focal spot size of about 3 µ Within the thickness of 2–4 µ of monolayered cells, larger areas of damage can be accounted for by divergence of the beam which is focused by a microscope objective of very short focal length. A threshold of biologic effectiveness is probably also involved.

scholarly journals Elucidating Chemical Structure at Station 11.3.1 at the Advanced Light Source

2014 ◽  
Vol 70 (a1) ◽  
pp. C1696-C1696
Author(s):  
Kevin Gagnon ◽  
Christine Beavers ◽  
Gregory Morrison ◽  
James Nasiatka ◽  
Simon Teat
Keyword(s):  
Light Source ◽  
Gas Flow ◽  
Structural Information ◽  
Spot Size ◽  
Complex Compounds ◽  
High Flux ◽  
Advanced Light Source ◽  
Recent Developments ◽  
Diamond Anvil ◽  
Focused Beam

One of the greatest challenges facing crystallographers has always been how to collect good data. This has become especially challenging as chemists are creating more complex compounds and looking to extract new exotic structural information from crystals which are getting smaller and smaller. Often, these crystals produce little or no diffraction on a laboratory diffractometer with long exposures. The past two decades have provided world-class synchrotron facilities to help solve these problems through a combination of high flux and a small focused beam spot size. Station 11.3.1 at the Advanced Light Source is a dedicated chemical crystallography beamline which has been developed and improved over the last decade to provide a global user base with a high flux, focused beam which is capable of doing more than just providing excellent data on weakly diffracting samples. Recent developments on station 11.3.1 include an environmental gas cell for studying of samples under evacuation, up to 1 atm of gasses and mixtures of gasses, and under gas flow; a diamond anvil cell for studying samples under applied pressures up to 10 GPa, a photodiode array for in-situ photocrystallography, as well as a tunable monochromator allowing energies between 6.5 and 22 keV. This poster will showcase the recent changes to station 11.3.1 as well as the future plans for upgrades.

Influence of Curvature Radius of 40Cr on Mechanical Properties of Laser Cladding Layer

2018 ◽  
Author(s):  
Mingsan Xu ◽  
Kerstern Malama ◽  
Bingbing Li
Keyword(s):  
Mechanical Properties ◽  
Laser Cladding ◽  
Laser Power ◽  
Gas Flow ◽  
High Speed Steel ◽  
Scanning Speed ◽  
Structure Design ◽  
Curvature Radius ◽  
Metal Powders ◽  
Optimal Parameters

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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