Effects of Different Shielding Gases and Power Waveforms on Penetration Characteristics and Porosity Formation in Laser Welding of Inconel 690 Alloy

Kuo, Tsung-Yuan; Lin, Yong-Ding

doi:10.2320/matertrans.48.219

Cited by 32 publications

(13 citation statements)

References 36 publications

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“…The samples welded under insufficient arc shielding gas had the greatest possibility for porosity 17 . In laser welding, transformation energy through keyhole mechanism was used, which resulted in maximum material melting.…”

Section: Macrostructures Of the Weldmentioning

confidence: 99%

Mechanical and Metallurgical Characterization of Laser Welding on P91 Ferritic Steel and Incoloy 800HT Dissimilar Joints

2018

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In this work, microstructural characterization and mechanical properties of P91 and Incoloy 800HT dissimilar laser beam welded joint were analyzed. In addition to that, metallographical studies were conducted using Optical microscopy, Scanning electron microscopy (SEM) equipped with Energy-dispersive X-ray spectroscopy (EDX) and X-Ray diffraction analysis (XRD). Effect of specific point energy on weld microstructure was predicted and it was compared with fusion zone hardness. The δ-ferrite content of the welds was predicted and it was correlated with the results measured by ferritoscope. Increase in heat input led to a minimal increase in the weld bead width and also the depth of penetration as predicted by microstructural studies. The traces of δ-ferrite in the interface of P91 side led to higher strength and microhardness of the weld. Failure of tensile specimens in the HAZ of Incoloy 800HT side was because of lower ferrite content (0 to 0.36) in that region and also due to the presence of the brittle intermetallic phases. The tensile strength of higher specific point energy welds was greater compared to other welds because of precipitation hardening and presence of δ-ferrite. Fractography results of fracture surfaces contain uniform dimples which showed that the failure took place in a ductile mode.

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Section: Macrostructures Of the Weldmentioning

confidence: 99%

Mechanical and Metallurgical Characterization of Laser Welding on P91 Ferritic Steel and Incoloy 800HT Dissimilar Joints

2018

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“…In contrast, it has been found that for lasers of shorter wavelengths such as YAG, fibre of disk laser (λ= 1.064 µm) the effect of shielding gas on process stability and weld geometry is minor and other parameters such as laser power density are dominant. For example, Kuo and Lin [11] reported that for a fixed set of welding parameters, similar penetration shapes and depths are obtained independently of the shielding gas employed. This is due to the fact that during Nd:YAG laser welding, laser energy absorption in the plume is very weak and therefore the plume volume has a lesser influence on the penetration depth.…”

Section: Introductionmentioning

confidence: 90%

Effect of shielding conditions on bead profile and melting behaviour in laser powder bed fusion additive manufacturing

Caballero

Suder

Chen

et al. 2020

Additive Manufacturing

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A series of experiments were performed using a 500W continuous wave fibre laser on a single powder bed layer using different processing variables. The aim was to investigate the effect of different shielding conditions on melting behaviour and bead profile in laser powder bed fusion (PBF). Through high-speed imaging, it was found that under an argon atmosphere a strong plasma plume is generated from the meltpool. Laser beam-plasma plume interactions caused strong instabilities during melting, including laser wandering, track instability and continuous fluctuations between melting regimes (conduction and keyhole). Hence, it was not possible to control the profile of the melted tracks under this condition. By using a helium atmosphere, a smaller plasma was obtained, reducing the disruptions caused by laser-plasma interactions. This led to a stable melting regime that allowed control of the melt bead profile.This condition was used to study the effect of laser-material fundamental interaction parameters on the bead geometry in powder bed melting. It was found that during melting of single tracks, the dominant regime of melting is conduction for the range of parameters tested.Penetration and melt width were found to increase with increasing energy density. For longer interaction times, melt widths were found to be up to ten times the size of the beam diameter used. Fluid flow modelling showed that this is due to strong melt flow as consequence of surface tension gradients generated by very high temperature gradients.

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“…One of his main conclusions is that Rayleigh absorption on nanoparticles is the dominant mechanism to consider in laser/vapour interaction. (Kuo and Lin, 2007) studied the influence of different shielding gas (argon, helium and nitrogen) during YAG pulsed laser welding of Inconel 690. They obtained similar weld beads dimensions and spatter generation whatever the protective gas and its flow rate but they reported that welding under helium generated a reduced vapour plume due to its higher thermal conductivity, and a faster expansion due to its lower density.…”

Section: Introductionmentioning

confidence: 99%

Influence of gas atmosphere (Ar or He) on the laser powder bed fusion of a Ni-based alloy

Traore

Schneider

Koutiri

et al. 2021

Journal of Materials Processing Technology

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The gaseous atmosphere plays a major role in the quality of the manufactured parts in Laser Powder Bed Fusion (L-PBF) by protecting the metal from high temperature oxidation. If argon and nitrogen are the most commonly used gases, helium has almost never been considered as a possible candidate as a chemically inert shielding gas. To provide a better understanding of the influence of the gas atmosphere on the process stability, a comparative study of L-PBF manufacturing under argon and helium atmospheres has been carried out, considering a nickelbased alloy Inconel® 625 and a single bead configuration. To this end, in-situ process measurements were carried out on a dedicated experimental setup. The melt pool behaviour, the expansion of the vapour plume and the amount of spatters were evaluated with high-speed imaging for the two gases considered, together with the final L-PBF bead dimensions. Results were also compared to single fusion beads carried out in an industrial L-PBF machine for a comparable range of volume energy densities. The influence of the shielding atmosphere on L-PBF single beads was as follows: (1) dimensions of beads were shown to be constant whatever the gas; (2) fewer and smaller spatters were produced under helium atmosphere, especially for high volume energy densities. Physical mechanisms were then discussed to understand those specific effects.

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Effects of Different Shielding Gases and Power Waveforms on Penetration Characteristics and Porosity Formation in Laser Welding of Inconel 690 Alloy

Cited by 32 publications

References 36 publications

Mechanical and Metallurgical Characterization of Laser Welding on P91 Ferritic Steel and Incoloy 800HT Dissimilar Joints

Mechanical and Metallurgical Characterization of Laser Welding on P91 Ferritic Steel and Incoloy 800HT Dissimilar Joints

Effect of shielding conditions on bead profile and melting behaviour in laser powder bed fusion additive manufacturing

Influence of gas atmosphere (Ar or He) on the laser powder bed fusion of a Ni-based alloy

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