scholarly journals Strategies for Increasing the Productivity of Pulsed Laser Cladding of Hot-Crack Susceptible Nickel-Base Superalloy Inconel 738 LC

2020 ◽  
Vol 4 (3) ◽  
pp. 84
Author(s):  
Christian Kästner ◽  
Matthias Neugebauer ◽  
Klaus Schricker ◽  
Jean Pierre Bergmann
Keyword(s):  
Aspect Ratio ◽  
Laser Pulse ◽  
Laser Cladding ◽  
Weld Seam ◽  
Pulsed Laser ◽  
Wetting Angle ◽  
Filler Material ◽  
Hot Wire ◽  
Hot Crack ◽  
Nickel Base

A novel repair strategy based on decoupled heat source for increasing the productivity of wire-assisted pulsed laser cladding of the γ’-precipitation strengthening nickel-base superalloys Inconel 738 low carbon (IN 738 LC, base material) and Haynes 282 (HS 282, filler material) is presented. The laser beam welding process is supported by the hot-wire technology. The additional energy is utilized to increase the deposition rate of the filler material by increasing feeding rates and well-defining the thermal management in the welding zone. The simultaneous application of laser pulse modulation allows the precise control of the temperature gradients to minimize the hot-crack formation. Accompanying investigations such as high-speed recordings and numerical simulations allow a generalized statement on the influence of the adapted heat management on the resulting weld seam geometry (dilution, aspect ratio and wetting angle) as well as the formation of hot-cracks and lack of fusion between base and filler material. Statistical analysis of the data—the input parameters like laser pulse energy, pulse shape, hot-wire power and wire-feeding rate in conjunction with the objectives like dilution, aspect ratio, wetting angle and hot-cracking behavior—revealed regression functions to predict certain weld seam properties and hence the required input parameters.

Effect of pulsed laser target cleaning on ionisation and acceleration of ions in a plasma produced by a femtosecond laser pulse

2005 ◽  
Vol 35 (10) ◽  
pp. 953-958 ◽  
Author(s):  
Roman V Volkov ◽  
A A Vorobiev ◽  
Vyacheslav M Gordienko ◽  
M S Dzhidzhoev ◽  
I M Lachko ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Femtosecond Laser Pulse ◽  
Pulsed Laser ◽  
Laser Target

On the advantages of nickel-base super-alloy laser cladding by direct powder injection

1999 ◽  
Author(s):  
B. Medres ◽  
L. Shepeleva ◽  
M. Bamberger ◽  
A. Weisheit
Keyword(s):  
Laser Cladding ◽  
Powder Injection ◽  
Nickel Base ◽  
Super Alloy

scholarly journals Pulsed Laser Cladding of Ni Based Powder

2017 ◽  
Vol 209 ◽  
pp. 012058 ◽  
Author(s):  
A Pascu ◽  
E M Stanciu ◽  
C Croitoru ◽  
I C Roata ◽  
M H Tierean
Keyword(s):  
Laser Cladding ◽  
Pulsed Laser

scholarly journals Effects of Pulse Duration and Heat on Laser-Induced Periodic Surface Structures

2020 ◽  
Vol 14 (4) ◽  
pp. 552-559
Author(s):  
Shuhei Kodama ◽  
Keita Shimada ◽  
Masayoshi Mizutani ◽  
Tsunemoto Kuriyagawa ◽  
◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Pulse Duration ◽  
Pulse Laser ◽  
Pulsed Laser ◽  
Laser Wavelength ◽  
Surface Structures ◽  
Pulsed Lasers ◽  
Efficient Technology ◽  
Periodic Surface ◽  
Ultrashort Pulsed Lasers

Compared with traditional nanotexturing methods, an ultrashort-pulsed laser is an efficient technology of fabricating nanostructures called laser-induced periodic surface structures (LIPSS) on material surfaces. LIPSS are easily fabricated when the pulse duration is shorter than collisional relaxation time (CRT). Accordingly, ultrashort-pulsed lasers have been mainly used to study LIPSS, but they unstably irradiate while requiring high costs. Although long-pulsed lasers have low cost and high stability, the phenomena (such as the effect of pulse duration, laser wavelength, and heat) of the LIPSS fabricated using short-pulsed lasers with the pulse duration close to the maximum CRT, which is greater than femtosecond, have not been clarified. However, the nanosecond pulse laser has been reported to produce LIPSS, but those were unclear and ununiform. In this study, the short-pulsed laser with the pulse duration of 20 ps, which is close to the maximum CRT, was employed to clarify the effects of pulse duration and heat on the fabrication of LIPSS and to solve problems associated with ultrashort-pulsed lasers. First, a finite-difference time-domain simulation was developed at 20-ps pulse duration to investigate the effects of irradiation conditions on the electric-field-intensity distribution. Subsequently, experiments were conducted using the 20-ps pulse laser by varying conditions. The aspect ratio of the LIPSS obtained was greater than that of the LIPSS fabricated using ultrashort-pulsed lasers, but LIPSS were not fabricated at 355- and 266-nm laser wavelength. In addition, the short-pulsed laser experienced thermal influences and a cooling material was effective for the fabrication of LIPSS with high-aspect-ratio. This demonstrates the effects of pulse duration close to the CRT and heat on the fabrication of LIPSS.

Comparative Study on Pulsed Laser Welding Strategies for Contacting Lithium-Ion Batteries

2016 ◽  
Vol 1140 ◽  
pp. 312-319 ◽  
Author(s):  
Patrick Schmitz
Keyword(s):  
Laser Beam ◽  
Comparative Study ◽  
Weld Seam ◽  
Laser Beam Welding ◽  
Pulsed Laser ◽  
Pulsed Laser Beam Welding ◽  
Joining Process ◽  
Suitable Process ◽  
Pulsed Laser Beam ◽  
Battery Cells

The transition towards renewable energy implicates more decentralized and time-dependent ways of energy generation. In order to deal with the resulting fluctuation in energy supply, local storage systems are necessary. Larger systems may consist of thousands of battery cells. Therefore, the reliable interconnection between the individual battery cells is the basic prerequisite for the production of these systems. It has been demonstrated that laser beam welding is a suitable process for the contacting of batteries. However, due to the high requirements regarding the heat input and the reproducibility of the joining process, further investigations are necessary. Within this work, experiments on pulsed laser beam welding of nickel-plated DC04 steel were conducted. Four different pulsed welding strategies were analyzed in a preliminary study in order to develop a method for obtaining suitable process parameters while reducing the amount of free parameters. Subsequently, a comparative study between the rectangular pulse, the shaped pulse, the spike pulse and the sloping pulse was carried out. The weld seam properties as well as the electrical and the mechanical properties of the connection joints were evaluated. The results presented in this paper indicate a high eligibility of pulsed laser beam welding as a joining process for the connection of battery cells. For all analyzed pulsed welding strategies a homogeneous weld seam without full penetration was observed. Similar electrical resistances for all strategies were measured despite the comparatively small total joint area for the discretely pulsed weld seams.

scholarly journals Depth Dependence and Keyhole Stability at Threshold, for Different Laser Welding Regimes

2020 ◽  
Vol 10 (4) ◽  
pp. 1487 ◽  
Author(s):  
Remy Fabbro
Keyword(s):  
Aspect Ratio ◽  
Laser Welding ◽  
Scaling Laws ◽  
Weld Seam ◽  
Operating Parameters ◽  
Cylindrical Shape ◽  
Aspect Ratios ◽  
Stability Issues ◽  
Keyhole Behavior ◽  
Ratio Range

Depending of the laser operating parameters, several characteristic regimes of laser welding can be observed. At low welding speeds, the aspect ratio of the keyhole can be rather large with a rather vertical cylindrical shape, whereas at high welding speeds, low aspect ratios result, where only the keyhole front is mainly irradiated. For these different regimes, the dependence of the keyhole (KH) depth or the keyhole threshold, as a function of the operating parameters and material properties, is derived and their resulting scaling laws are surprisingly very similar. This approach allows us to analyze the keyhole behavior for these welding regimes, around their keyhole generation thresholds. Specific experiments confirm the occurrence and the behavior of these unstable keyholes for these conditions. Furthermore, recent experimental results can be analyzed using these approaches. Finally, this analysis allows us to define the aspect ratio range for the occurrence of this unstable behavior and to highlight the importance of laser absorptivity for this mechanism. Consequently, the use of a short wavelength laser for the reduction of these keyhole stability issues and the corresponding improvement of weld seam quality is emphasized.

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