803056 wrote:
"He welded a short bead on the backing and we quenched it in water, dried it, knocked off the slag and submerged it in the baby oil. Many of you already know what the expected outcome was; it gave off a cloud of tiny bubbles of hydrogen gas."
I hate to show my ignorance but here goes. Why baby oil? Will it work with other fluids? How long will it vent hydrogen? Will it vent hydrogen if cooled slowly? Where is the hydrogen coming form? Is the metal porous? Sounds like a good parlor trick to me.
I believe in following procedures when called for. I am with you there. But I have welded up stuff with 7018's that were not kept in ovens. Bet I'm not the only one. I'm wondering what the difference is in weld strength in Lo Hy and High Hy rods are?
From Lincoln at this link
http://www.lincolnelectric.com/knowledge/articles/content/fillermetals.asp(snip)
Can Hydrogen Affect Mechanical Properties?
The influence of hydrogen can be observed in mechanical testing; however, its effects on the test results are limited. A high hydrogen content in a tensile specimen can produce "fish-eyes" on the fracture surface as seen in Figure 1.
Additionally, the presence of hydrogen can reduce ductility (as expressed by elongation and reduction in area). Hydrogen, however, does not typically influence the impact toughness, ultimate tensile strength or yield strength results. It is only in severe cases that it can influence the ultimate tensile strength.
Since low hydrogen SMAW electrodes like E7018 are also required to have a minimum specified level of Charpy V-notch (CVN) impact energy, low hydrogen is sometimes equated with a minimum CVN level. This has led some people to specify low hydrogen when the real desire is for notch toughness. The better approach is to specify notch toughness requirements since there is no automatic link between low diffusible hydrogen content in the weld and CVN values. Actually, some deposits with high hydrogen levels can deliver relatively high levels of notch toughness. For example, the E6010 classification (non-low hydrogen, 30-50 mL/100g) has a minimum CVN requirement of 20 ft-lbs at minus 20°F.
(snip)
A little ductility may be lost. We hope to make welds that don't fracture so fish-eyes should not be much of a big deal.
So in the real word, what is the practical difference in 7018's stored properly and 7018's that are not as well kept?