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I'm not referring to the wire filler specifically although, AWS A5.18 and A5.28 must be met @ minimum...
What I am referring to is the Dew point in the gas shielding which is definitely an important consideration when GMA Welding and is for the most part one of the least of considerations when formulating the proper "ingredients to a recipe" to use for GMAW... In fact the only time it is seriously considered prior to the actual commencement of welding operations is when the EOR specifies it...
For example: in AWS D1.3 Structural Welding Code—Sheet Steel-1. General Provisions Scope - 1.4.6.2 Shielding Media.
A gas or gas mixture used for shielding in GMAW, FCAW, when required, or GTAW, shall be of a welding grade having a dew point of –40°F (–40°C) or lower. When requested by the Engineer, the gas manufacturer shall furnish certification that the gas or gas mixture meets the procurement specification and will meet the dew point requirement.
The other consideration of moisture control is when using uncoated filler wire which will for the most part be more suspect to acquiring moisture when exposed in relatively high humidity environments also....
In emphasizing moisture control as opposed to baking the filler metal so you don't have an argument with me concerning the possibility or just the rationale for drying used GMAW wire rolls in an oven... What I'm alluding to is something like an old refrigerator with a working light bulb configured sort of like what Al describes when he stores stuff to protect from excessive humidity...
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This is from Arcelor Mittal:
"How to Control Hydrogen in Electrodes and Gases
As with low hydrogen covered electrodes, excessive hydrogen from electrodes or gases used for gas metal arc or flux cored arc welding can cause heat-affected-zone or weld-metal cracking.
Hydrogen from electrodes comes from contaminants, such as drawing compounds or grease, trapped on the electrode surface. In addition, for flux cored electrodes, hydrogen can come from any moisture retained or absorbed by the core materials. When gas metal arc or flux cored arc welding electrodes deposit weld metal containing greater than 5 ml/100 gm diffusible hydrogen, there is a possibility of cracking in welds of many alloy steels including the “T-1” steels.
To avoid this possibility, the electrodes should be procured with the electrode manufacturer’s guarantee that the total diffusible hydrogen content of the deposit is not more than 5 ml/100 gm.
Shielding gases for gas metal arc or flux cored arc welding of many alloy steels including the “T-1” Steels should be welding quality low-moisture-content gases
{dew point: -40oF or lower} to minimize the possibility of heat-affected-zone and weld-metal cracking...
Summary of Rule 1
1. For shielded metal arc welding, use only low hydrogen electrodes that provide weld metal of suitable strength and toughness – and keep them dry...
2. For submerged arc welding, use only hydrogen-controlled electrodes and fluxes that provide weld metal of suitable strength and toughness...
3. For gas metal arc and flux cored arc welding, use only hydrogen-controlled electrodes and gases that provide weld metal of suitable strength and toughness..."
Well, that's it for now... This is a topic that should be discussed more often.
Respectfully,
Henry