A Study of the Effect of Post-Heating Pulse on Hot Cracking Susceptibility in Pulsed Laser Welding of Invar Alloy

2019 ◽  
Vol 35 (4) ◽  
pp. 338-343 ◽  
Author(s):  
DongSheng Zhao ◽  
ZhenYu Huang ◽  
YuJun Liu ◽  
Tangjun Miao
Keyword(s):  
Laser Welding ◽  
Cooling Rate ◽  
Pulsed Laser ◽  
Welding Process ◽  
Hot Cracking ◽  
Invar Alloy ◽  
Heating Pulse ◽  
Welding Temperature ◽  
Welding Condition ◽  
Pulsed Laser Welding

Hot cracking is one of the major challenges in laser welding of Invar alloy. In this study, welding hot cracking susceptibility experiments are conducted with fish-bone‐type Invar alloy sheets under pulsed laser welding condition. The pulse wave consists of two distinct power levels: welding pulse and post-heating pulse. The welding temperature field can be controlled by changing the duration of the post-heating pulse. The results of experimental measurements and finite element method calculation show that increasing of the post-heating pulse duration leads to a decline in the cooling rate of weld metal within the brittle temperature range, although the welding hot cracking susceptibility decreases at first and then increases. Neither the heat input nor the cooling rate is the only decisive factor for hot cracking during the welding process.

Effect of Preheating on Hot Cracking Susceptibility in Pulsed Laser Welding of Invar Alloy

2021 ◽  
pp. 1-9
Author(s):  
DongSheng Zhao ◽  
Liangliang Wu ◽  
TianFei Zhang ◽  
Lele Kong ◽  
YuJun Liu
Keyword(s):  
Laser Welding ◽  
Pulse Duration ◽  
Pulse Wave ◽  
Pulsed Laser ◽  
Fish Bone ◽  
Hot Cracking ◽  
Invar Alloy ◽  
Welding Temperature ◽  
Pulsed Laser Welding ◽  
Measurement Results

Hot cracking is a serious problem in welding of Invar alloy. The weld hot cracking susceptibility of Invar was evaluated using pulsed laser welding on fish-bone sheet experiment. The pulse wave consisted of preheating pulse and welding pulse. Hot cracks that formed along the grain boundary propagated from the weld upper surface to the inside. The experiments show that adding a preheating pulse can effectively reduce the hot cracking susceptibility of Invar alloy. Finite Element Modeling (FEM) calculations and experimental measurement results show that the welding temperature gradient and cooling rate decrease with increasing preheating pulse duration. However, as the preheating pulse duration increases, the hot cracking susceptibility of the Invar alloy does not decrease all the time, but decreases first and then increases. This is because the increase of heat input leads to the increase of shrinkage plastic strain when the preheating pulse duration increases. The maximum tensile strength of the butt welded joint of the Invar alloy was 467.3 MPa, which is 92.3% of the base metal when the preheating pulse duration is 3 ms.

scholarly journals Fuzzy C-Means Partition Cluster Analysis and Validation Studies on a Subset of CiteScore Dataset

2019 ◽  
Vol 8 (9S3) ◽  
pp. 105-107
Keyword(s):  
Cluster Analysis ◽  
Laser Welding ◽  
Validation Studies ◽  
Welded Joint ◽  
Experimental Studies ◽  
Pulsed Laser ◽  
Welding Process ◽  
Pulsed Laser Welding ◽  
Fuzzy C Means

The article deals with promising areas of application of pulsed laser welding for products made of silver-based alloys. The results of experimental studies to improve the quality of the welded joint and the efficiency of the welding process with the use of activated absorption additives are presented

scholarly journals Improving the Quality of Welded Joints in Laser Welding of Silver Products

2019 ◽  
Vol 8 (9S3) ◽  
pp. 102-104
Keyword(s):  
Laser Welding ◽  
Welded Joints ◽  
Experimental Studies ◽  
Pulsed Laser ◽  
Welding Process ◽  
Pulsed Laser Welding

The article deals with promising areas of application of pulsed laser welding for products made of silver-based alloys. The results of experimental studies on the choice of modes of pumping, defocusing to improve the quality of the weld and the efficiency of the welding process.

A Study of Forces and Motion Generated During Pulsed Laser Welding of Optical Packages

1991 ◽  
Vol 113 (4) ◽  
pp. 343-349 ◽  
Author(s):  
S. Rangwala
Keyword(s):  
Thermal Stress ◽  
Laser Beam ◽  
Laser Welding ◽  
Relative Motion ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Welding Process ◽  
Stress Waves ◽  
Pulsed Laser Welding ◽  
Welding Operation

This paper presents an analysis of forces and motions generated during interaction of pulsed laser energy with materials. The effects of this interaction on the subsequent dynamics of the material receiving this energy have important implications in the manufacture of laser diode packages. Small motions which occur during laser welding of the package assembly can cause serious losses in the amount of coupled power, thus degrading the performance of the package. This work is aimed at understanding how these movements occur. Various quantities such as force, acceleration and coupled power variations were measured during a laser welding operation. These measurements establish that significant thermal stress waves are generated during the welding process. However, the final relative motion between cylindrical specimens which are butt-welded by a laser beam occurs due to rapid cooling and shrinkage of the weld pool at the interface of the two specimens.

scholarly journals Pulsed Laser Welding Applied to Metallic Materials—A Material Approach

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 640
Author(s):  
Mariane Chludzinski ◽  
Rafael Eugenio dos Santos ◽  
Cristina Churiaque ◽  
Marta Ortega-Iguña ◽  
Jose Maria Sánchez-Amaya
Keyword(s):  
Laser Welding ◽  
Contact Process ◽  
Weld Zone ◽  
Pulsed Laser ◽  
Welding Process ◽  
Industrial Sector ◽  
Dissimilar Joints ◽  
Pulsed Laser Welding ◽  
Strength Performance ◽  
Process Characteristics

Joining metallic alloys can be an intricate task, being necessary to take into account the material characteristics and the application in order to select the appropriate welding process. Among the variety of welding methods, pulsed laser technology is being successfully used in the industrial sector due to its beneficial aspects, for which most of them are related to the energy involved. Since the laser beam is focused in a concentrated area, a narrow and precise weld bead is created, with a reduced heat affected zone. This characteristic stands out for thinner material applications. As a non-contact process, the technique delivers flexibility and precision with high joining quality. In this sense, the present review addresses the most representative investigations developed in this welding process. A summary of these technological achievements in metallic metals, including steel, titanium, aluminium, and superalloys, is reported. Special attention is paid to the microstructural formation in the weld zone. Particular emphasis is given to the mechanical behaviour of the joints reported in terms of microhardness and strength performance. The main purpose of this work was to provide an overview of the results obtained with pulsed laser welding technology in diverse materials, including similar and dissimilar joints. In addition, outlook and remarks are addressed regarding the process characteristics and the state of knowledge.

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