Hydrogen embrittlement

Date 08-14-2008 00:40

Hello,

Is it safe to weld stainless material with an Argon/Hydrogen 95/5 mix gas? I know it is common to see this mix used in Orbital welding applications with an ID purge flow.

But in a fillet application welding the filler material to the base; Could it increase the chance of embrittlement or even reduce the strength of the weld using the mix gas?

By sid mehta Date 08-14-2008 06:35

In Argon 95 % and Hydrogen 5% the hydrogen helps increase weld pool fluidity , create a hotter arc and it combines with oxygen in the immediate vicinity of the weld pool forming H2O thereby reducing oxidation giving a cleaner weld. It is recommended for plasma and orbital welding of austenitic steels.
Generally HIC is not a problem associated with austenitic steels .IGCC , SCC ,Hot cracking and Sigma phase formation are more likely

Susceptibility to cracking in HAZ due to HIC is greatest in martensitic microstructure and least in ferritic. As a thumb rule it is assumed that steel is not susceptibile to cracking if its CEiiw is < o.4 and its HAZ hardness is < 350 VHN

By ravi theCobra (**)

Date 08-14-2008 17:09

You haven't said the welding process you are using -

This is great on an austenetic material with TIG but watch out on steel with mig

By TheSavvy1 (**)

Date 08-19-2008 01:27

Thanks,

I was unsure about using the mix gas and adding the filler material in a TIG app. I had never scene embriddlement welding stainless just thought I would ask the pro's.

By 522029

Date 08-19-2008 22:16

Is that 5% hydrogen or did you mean to say helium?

Griff