抄録
Cold cracking sensibility is severe problem in the welding fabrication of large-scale steel structures. In order to solve this
problem, a low hydrogen welding process using a special torch has recently been developed and shown to be effective for cold
cracking. In this process, a torch having a double nozzle is applied to perform welding while sucking a part of the shielding gas from
the inner nozzle. Due to the feature of the process, there is a concern about shieldability, but there have been no reports on this point.
Therefore, in this study, the shielding property against the lateral wind was evaluated by fluid simulation. The calculated results of
the model were in good agreement with the observed results by the Shadowgraph method and the nitrogen content of weld metal. In
addition, a comparison simulation with a conventional torch shows that this process has no clear difference in shielding performance
compared with the conventional process, and good shielding performance is ensured. This is because the torch structure in which
the inner nozzle protrudes also effectively works for the shielding property in order to improve the reduction effect of diffusible
hydrogen.
