The elimination of pores in laser welds of AISI 304 plate using different shielding gases

Sun, Junhao; Nie, Pulin; Feng, Kai; Li, Zhuguo; Guo, Baochao; Jiang, E.Y.

doi:10.1016/j.jmatprotec.2017.05.011

“…Figure 2. Coupling of physical phenomenas according to Traidia, 2011 [15] The thermo-mechanical and metallurgical approach, TMM, is coupling heat transfer, metallurgical transformations and solid mechanics [15] and is more widely used in practice, as it easier to obtain [15,17,26].…”

Section: Modelling Weldingmentioning

confidence: 99%

“…Welding defects, such as porosity and undercuts, can be covered using the comprehensive heat and fluid flow approach [17]. Porosity is a significant problem in laser welding of aluminium and high-strength steels [17,26]. Porosity can be reduced with optimised welding parameters that can be obtained with numerical simulation.…”

Section: Modelling Weldingmentioning

confidence: 99%

Numerical simulation of laser welded joints: modern fatigue analysis methodology

Kokko¹,

Vaara

²

,

Kuivaniemi

³

et al. 2020

RakMek

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Welding always induces discontinuities and imperfections in the structure that allows for potential fatigue cracks. Welding eﬀects thermal strains, which yield to residual stresses of the structure that have a noticeable eﬀect on the fatigue behaviour of the structure. Welding inexorably leads to microstructure and geometry changes in the welding region. Material internal changes, residual stresses and microstructural changes can be simulated numerically, and the simulation results can be used in cyclic loading analysis in FEA.

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“…Both the weld penetration and weld area increased with increase of nitrogen in argon-based shielding gas. Moreover, it was reported that the pores in the laser welds could be eliminated by using N 2 as the shielding gases [15]. Zong et al studied the influence of shielding gas on undercut defects in GMAW and found that the undercut defects could be significantly reduced by increasing the CO 2 content [16].…”

Section: Introductionmentioning

confidence: 99%

Effects of Active Gases on Droplet Transfer and Weld Morphology in Pulsed-Current NG-GMAW of Mild Steel

Liu

¹

,

Tang

²

,

Xu

³

et al. 2021

Chin. J. Mech. Eng.

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The current research of narrow-gap gas metal arc welding (NG-GMAW) primarily focuses on improving the sidewall fusion and avoiding the lack-of-fusion defect. However, the high cost and operation difficulty of the methods limit the industrial application. In this study, small amount of active gases CO2 and O2 were added into pure argon inert shielding gas to improve the weld formation of pulsed-current narrow-gap gas metal arc welding (NG-GMAW) of mild steel. Their effects on droplet transfer and arc behavior were investigated. A high-speed visual sensing system was utilized to observe the metal transfer process and arc morphology. When the proportion of CO2, being added into the pure argon shielding gas, changes from 5% to 25%, the metal transfer mode changes from pulsed spray streaming transfer to pulsed projected spray transfer, while it remains the pulsed spray streaming transfer when 2% to 10% O2 is added. Both CO2 and O2 are favorable to stabilizing arc and welding process. O2 is even more effective than CO2. However, O2 is more likely to cause slags on the weld surface, while CO2 can improve the weld appearance in some sense. The weld surface concavity in NG-GMAW is greatly influenced by the addition of active gas, but the weld width and weld penetration almost keep constant. This study proposes a new method which is beneficial to improving the weld bead formation and welding process stability.

show abstract

“…Both the weld penetration and weld area increased with increase of nitrogen in argon-based shielding gas. Moreover, it was reported that the pores in the laser welds could be eliminated by using N2 as the shielding gases [15]. Zong et al studied the influence of shielding gas on undercut defects in GMAW and found that the undercut defects could be significantly reduced by increasing the CO2 content [16].…”

Section: Introductionmentioning

confidence: 99%

Effects of active gases on droplet transfer and weld morphology in pulsed-current NG-GMAW of mild steel

Liu

¹

,

Tang

²

,

Xu

³

et al. 2021

Preprint

0

View full text Add to dashboard Cite

The current research of narrow-gap gas metal arc welding (NG-GMAW) primarily focuses on improving the sidewall fusion and avoiding the lack-of-fusion defect. However, the high cost and operation difficulty of the methods limit the industrial application. In this study, small amount of active gases CO2 and O2 were added into pure argon inert shielding gas to improve the weld formation of pulsed-current narrow-gap gas metal arc welding (NG-GMAW) of mild steel. Their effects on droplet transfer and arc behavior were investigated. A high-speed visual sensing system was utilized to observe the metal transfer process and arc morphology. When the proportion of CO2, being added into the pure argon shielding gas, changes from 5% to 25%, the metal transfer mode changes from pulsed spray streaming transfer to pulsed projected spray transfer, while it remains the pulsed spray streaming transfer when 2% to 10% O2 is added. Both CO2 and O2 are favorable to stabilizing arc and welding process. O2 is even more effective than CO2. However, O2 is more likely to cause slags on the weld surface, while CO2 can improve the weld appearance in some sense. The weld surface concavity in NG-GMAW is greatly influenced by the addition of active gas, but the weld width and weld penetration almost keep constant. This study proposes a new method which is beneficial to improving the weld bead formation and welding process stability.

show abstract

The elimination of pores in laser welds of AISI 304 plate using different shielding gases

Cited by 39 publications

References 15 publications

Numerical simulation of laser welded joints: modern fatigue analysis methodology

Numerical simulation of laser welded joints: modern fatigue analysis methodology

Effects of Active Gases on Droplet Transfer and Weld Morphology in Pulsed-Current NG-GMAW of Mild Steel

Effects of active gases on droplet transfer and weld morphology in pulsed-current NG-GMAW of mild steel

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