Research on the Effects of Welding-wire-related Factors Affecting Diffusible Hydrogen Content

MUKAI, Naoki; Suzuki, Reiichi

doi:10.2207/qjjws.35.102

Cited by 4 publications

(3 citation statements)

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“…At a suction gas rate of 10 l/min, η sc was 48.8% against 59.6% at a suction gas rate of 3 l/min, and thus this leads to a difference of X H2Oave between two suction rate cases. The H 2 O in the gas was transported by advection and diffusion, as presented in Equation (5). If diffusion plays an important role in the transport process of H 2 O, the increase in the gas flow velocity in the vicinity around the suction nozzle is thought to increase η sc .…”

Section: Resultsmentioning

confidence: 99%

“…When the effect of the shielding gas flow was stronger than that of the suction gas, the suction limit height moved to a lower location, leading to a smaller X H2Oave . (5) This method was suggested to be particularly effective for reducing the diffusible hydrogen content to extend the suction nozzle length. However, further development to prevent spatter attachment to the nozzle is required.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the great part of this gas spreads out with shielding gas to the surroundings without entering the weld pool. Mukai et al reported the diffusible hydrogen content increased almost in proportion to welding current under a constant CTWD, which is thought to be caused by an increase in WFS [5]. The relevance of the effect of main welding parameters on the diffusible hydrogen content was summarized by Fydrych et al [6].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of the Behavior of Hydrogen Source in a Novel Welding Process to Reduce Diffusible Hydrogen

et al. 2020

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This study aims to reduce the diffusible hydrogen content in deposited metal during gas metal arc welding (GMAW) and flux-cored arc welding (FCAW) which induces cold cracking. To achieve this, a novel welding torch with a dual gas nozzle has been developed. This special welding torch decreases the hydrogen source gas evaporated from a welding wire by the suction from the inner gas nozzle. In order to improve the suction efficiency of this evaporated gas, precise control of the suction gas flow is indispensable. In this paper, a simplified numerical simulation model of this process has been described. This model can take account of the evaporation of the hydrogen source gas from the wire while simulating the behavior of the shielding gas and the arc. Using this model, the effect of suction nozzle structure and torch operating conditions on suction gas flow pattern and suction efficiency was also investigated to understand the process mechanism. Furthermore, the diffusible hydrogen content in deposited metal was measured by chromatography as a validation step. Results show that some of the shielding gas introduced from a shielding nozzle was drawn inward and also branched into an upward flow that was sucked into the suction nozzle and a downward flow to a base metal. This branching height was defined as the suction limit height, which decisively governed the suction efficiency. As a result, in order to reduce the diffusible hydrogen, it was suggested that the suction limit height should be controlled towards below the wire position, where the evaporation rate of the hydrogen source gas peaks through optimization of the suction nozzle design and the torch operating conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%