[MW:10681] Re: GMAW short circuit Welders Qualification

GMAW process changes the characteristics as the voltage and current
are varied. When the voltage is in the 17-18 volt range, the mode of
transfer is short circuit. This is a very low heat input process that
is used for very thin materials and root pass on pipe. The concern is
that you can have non-fusion. As the voltage is raised the mode of
transfer changes to globular which generates an abnormal amount of
spatter. When you get to the 26-28 volt range the mode of tranfer
becomes spray arc. The concern of non-fusion goes away with GMAW
spray transfer. This is why the codes (ASME and AWS) require bend
tests for GMAW short circuit. X-ray does not do a good job of picking
up non-fusion where as bend test will definately identify it.

I hope this helps.

David Landon
Vermeer Corporation

On Apr 14, 11:50 am, Zakaria ghrab <zakaria.gh...@gmail.com> wrote:
> Hi all,
>
> According ASME section IX, in case of welders Qualification of GMAW process
> - short circuit transfer mode, Radiography is not applicable and we must do
> Mechanical tests.
>
> Need just to know what's exactly Short circuit transfert mode and how it can
> defferenciate of others ! by current range ?
>
> Regards.
>
> --
> *زكرياء غراب
> **GHRAB Zakaria** *
> مسؤول عن الجودة
> QA/QC SENAD
> مشروع المحطة الحرارية ـ الوحدة الرابعة
> المحمدية ـ المغرب

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