scholarly journals Influence of laser power and welding speed on dendrite structure growth of low power pulsed laser welded super alloy

2021 ◽  
Vol 1104 (1) ◽  
pp. 012019
Author(s):  
Uday Kumar ◽  
Somnath Chattopadhyaya ◽  
A K Das ◽  
Ratnesh Kumar ◽  
Shubham Sharma ◽  
...  
Keyword(s):  
Low Power ◽  
Welding Speed ◽  
Laser Power ◽  
Pulsed Laser ◽  
Dendrite Structure ◽  
Super Alloy

Machining and Characterization of Deep Micro Holes on Super Alloy Processed by Millisecond Pulsed Laser

2016 ◽  
Vol 703 ◽  
pp. 34-38 ◽  
Author(s):  
Yun Long Wang ◽  
Lin Zhong Zhu ◽  
Cai Yan Chen ◽  
Zhi Chen Liu ◽  
Wei Xin Ren ◽  
...  
Keyword(s):  
Laser Power ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Processing System ◽  
Longitudinal Section ◽  
Recast Layer ◽  
Numerical Control ◽  
Micro Cracks ◽  
Micro Holes ◽  
Super Alloy

In this study, a series of deep micro holes were machined on thick GH4169 super alloy by the trepan drilling, using a millisecond pulsed laser which equipped to the numerical control processing system. The microstructure of the holes including surface and longitudinal morphologies, diameter, taper, circularity, micro cracks and recast layer were systematically characterized. The surface morphology and the longitudinal section of the drilled holes were observed by Scanning Electron Microscope and 3D Laser Scanning Confocal Microscope. The method of Minimum circumcircle method was employed to evaluate the entrance and exit end circularity. The results showed that the melt and spattering accumulating around the holes decreased with the augment of laser power. The diameter of the entrance showed an increasing tendency with the growing of laser power, but the exit end was not seriously affected by the power. The micro cracks and recast layer could be found obviously, the micro cracks appeared in those zones which thermal stress concentrated, the thickness of recast layer is about 20μm and the taper and circularity were optimized at a laser power of 80-100W.

scholarly journals Power controllable gain switched fiber laser at ~ 3 μm and ~ 2.1 μm

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yiwen Shi ◽  
Jianfeng Li ◽  
Chendong Lai ◽  
Hanlin Peng ◽  
Chen Zhu ◽  
...  
Keyword(s):  
Pump Power ◽  
Low Power ◽  
Fiber Laser ◽  
Output Power ◽  
Laser Power ◽  
Continuous Wave ◽  
Pulsed Laser ◽  
Maximum Output ◽  
Pump Source

AbstractBased on a hybrid pumping method consisting of a 1150 nm continuous-wave pump source and a 1950 nm pulsed pump source, we demonstrate a power controllable gain-switched fiber laser in dual wavebands at ~ 3 μm and ~ 2.1 μm. Different pumping schemes for pumping a Ho3+-doped ZBLAN fiber are studied. Using only the 1950 nm pulsed pump source, ~ 2.1 μm gain-switched pulses with single and double pulses are obtained separately at different pump powers. This phenomenon indicates that the 1950 nm pulsed pump source acts as a modulator to trigger different states of the ~ 2.1 μm pulses. Moreover, by fixing the 1150 nm pump power at 3.259 W and adjusting the 1950 nm pump power, the output power of the ~ 2.1 μm gain-switched pulsed laser is flexibly controlled while the ~ 3 μm laser power is almost unchanged, inducing the maximum output powers of 167.96 mW and 260.27 mW at 2910.16 nm and 2061.65 nm, respectively. These results suggest that the comparatively low power of the ~ 2.1 μm gain-switched pulsed laser in dual-waveband laser can be efficiently overcome by reasonably controlling the 1950 nm pump power.

Feasibility Study of Low Power Fiber Laser Welding AA2024 and AA7075 Alloys T-Joint

2016 ◽  
Vol 701 ◽  
pp. 182-186 ◽  
Author(s):  
Shamini Janasekaran ◽  
Ai Wen Tan ◽  
Farazila Yusof ◽  
Mohd Hamdi Abdul Shukor
Keyword(s):  
Laser Welding ◽  
Low Power ◽  
Fiber Laser ◽  
Welding Speed ◽  
Laser Power ◽  
Shielding Gas ◽  
Power Laser ◽  
Fiber Laser Welding ◽  
Full Penetration ◽  
Dissimilar Aluminum Alloys

Dissimilar aluminum alloys, AA2024-0 and AA7075-T6 were laser welded on both sides in a T-joint configuration using a low power fiber laser. The effect of welding speed (9, 12, 15, 18 and 21 mm/s) on weldability was evaluated at laser power of 270W with argon gas as the shielding gas. The sample welding angle was fixed at 45° with an interval of 180 seconds between each welding pass. Macrograph observations revealed that full penetration with pore free weld of these dissimilar joint was obtained at the laser parameters of 270 W and 9 mm/s, suggesting that lower welding speed is preferred during low power laser welding.

EXPERIMENTAL STUDY ON THE CO2 LASER CUTTING OF NOVEL POLYAMIDE 6/FLUOROELASTOMER THERMOPLASTIC ELASTOMERIC BLENDS

2015 ◽  
Vol 88 (1) ◽  
pp. 125-137 ◽  
Author(s):  
Shib Shankar Banerjee ◽  
Anil K. Bhowmick
Keyword(s):  
Low Power ◽  
Co2 Laser ◽  
Process Parameters ◽  
Laser Power ◽  
Laser Cutting ◽  
Manufacturing Industry ◽  
Cutting Speed ◽  
Polyamide 6 ◽  
Thermoplastic Elastomers ◽  
Dynamic Vulcanization

ABSTRACT The application of the low-power CO2 laser-cutting process to fluoroelastomer (FKM), polyamide 6 (PA6), PA6/FKM thermoplastic elastomers (TPEs), and their thermoplastic vulcanizate (TPV) is reported. The main laser process parameters studied were laser power, cutting speed, and material thickness. The value of the top and bottom widths of the slit that were formed during laser cutting (kerf width), melted transverse area, and melted volume per unit time were measured and analyzed. Interestingly, TPE showed a smaller melted area and melted volume per unit time when compared with those values with PA6. Dynamic vulcanization further decreased these values. For example, the melted areas of PA6 and TPE were 510 × 10−3 mm2 and 305 × 10−3 mm2, respectively, which reduced to 238 × 10−3 mm2 for TPV at 40 W laser power. FKM showed the lowest value (melted area of 180 × 10−3 mm2). In addition, the output quality of the cut surface was examined by measuring the root mean square (RMS) roughness of the cut edges and heat-affected zone (HAZ). The obtained results indicated that the dimension of the HAZ and RMS roughness largely decreased in TPE when compared with PA6. For example, the HAZ of PA6 was 700 μm, which decreased to 230 μm for TPE at 40 W laser power. On the other hand, HAZ was nonexistent for FKM. Infrared spectroscopic analysis showed that there was no structural change of TPE or pristine polymers after applying the low-power CO2 laser on the surface of materials. CO2 laser cutting will be a new technique in this industry, and this analysis will assist the manufacturing industry to choose a suitable laser system with exhaustive information of process parameters for cutting or machining of rubber, TPEs, and TPVs.

Experimental Study on Testing Ni-Containing Stainless Steel Protective Coatings by Pulsed Laser Scratching

2010 ◽  
Vol 43 ◽  
pp. 651-656
Author(s):  
Ai Xin Feng ◽  
Yu Peng Cao ◽  
Chuan Chao Xu ◽  
Huai Yang Sun ◽  
Gui Fen Ni ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Power Density ◽  
Laser Power ◽  
Protective Coatings ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
Laser Power Density ◽  
The Matrix ◽  
The Impact

In the experiment, we use pulsed laser to conduct discrete scratching on Ni-containing stainless steel protective coatings to test residual stress situation after the matrix is scratched; then to analyze the the impact of the impact stress wave on coating - substrate bonding strength according to the test results, finally to infer the laser power density range within which it occurs coating failure. The study shows that: after laser discrete scratching, the residual stress of the center of the laser-loaded point on matrix surface gradually reduces when the pulsed laser power density increases. The matrix produces a corresponding residual compressive stress under the laser power density reaches a certain value. The actual failure threshold values are 12.006 GW/cm2, 11.829GW/cm2 and 12.193GW/cm2 measured by the three-dimensional topography instrument testing the discrete scratch point of three groups of samples and verified by using a microscope

scholarly journals Temperature Calibration Measurements based on Laser-Induced Phosphorescence Technique for Combustion Applications

2015 ◽  
Vol 10 (1) ◽  
Keyword(s):  
Laser Radiation ◽  
Laser Beam ◽  
Intensity Ratio ◽  
Laser Power ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Temperature Calibration ◽  
Phosphor Powder ◽  
Calibration Methods

Phosphor powder and phosphor-binder mixtures are successfully employed for temperature calibration measurements by using laser-induced phosphorescence (LIP) technique with an emphasis on higher precisions and accuracies than other non-intrusive methods. The phosphorescence intensities are used to perform these calibrations in three different strategies. The influence of laser power regular changes on particles heating and the calibration analyses is also carried out. A pulsed laser at 355 nm was used for exciting specimens of the phosphor powder as well as the phosphor-binder mixtures. The laser beam was directed onto the specimens and varied in three laser power levels (LPLs). The samples were kept in an oven with temperatures ranging from room temperature up to 1800 °C. The three strategies which are expressed in terms of non-dimensional intensity versus wavelength (NDI-W), normalised intensity (NI) and intensity ratio (IR) were used for the calibration assessments. A modified IR was compared with two different IRs. A precision of around ± (0.50-1.41)% was attained for different calibration methods. This research confirmed that these calibrations are possible using three different strategies, given high precisions and accuracies. The laser power alternations influenced the NI and do affect neither the NDI-W nor the IR curves. The laser radiation does not play any role for heating the particles of the studied powder.

Surface Quality of Pulsed Laser Cutting of Difficult to Machine Steel

2011 ◽  
Vol 299-300 ◽  
pp. 1016-1019
Author(s):  
Tie Jun Li ◽  
Jing Tang ◽  
Li Jun Yan ◽  
Yang Wang
Keyword(s):  
Surface Quality ◽  
Laser Cutting ◽  
Pulsed Laser ◽  
Cutting Parameters ◽  
Quality Factors ◽  
Good Separation ◽  
Machine Steel ◽  
Optimum Cutting ◽  
Super Alloy

This paper presented the experiments of Nd:YAG pulsed laser cutting of titanium alloy, super-alloy and stainless steel sheet, and investigated the influences of different laser cutting parameters on the surface quality factors focusing surface morphology. In comparison with air-, argon- and nitrogen-assisted laser cutting, argon-assisted laser cutting comes with unaffected surface quality and is suitable for laser cutting with subsequent welding requirement. With analyzing the interaction between pulses overlapping rate and energy, the results show that medium pulse overlapping rate and lower pulse rate helps to improve the surface roughness with pulsed laser cutting. And the results would be beneficial to find optimum cutting parameters for good separation surface.

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