Rods for the Hobbyist - Part 2
In part one I said it is important
to receive the rods*** sealed in their packets. The reason for this is
7018 is a low hydrogen rod. It does not tolerate moisture and must be kept dry
before use. If not, when welding it will allow for pitting and porosity (worm
holes) which are weld defects. This happens when moisture gets in the flux coating
and allows hydrogen to adversely affect the weld pool. I'll discuss other defects
in more detail in a different article.
7018 rods that haven't been dried
properly may make a good looking weld at first that will be subject to longitudinal
cracking either right after welding, or later on. Longitudinal cracking is where
a crack starts and follows the length of the weld.
Whether you're using
7018 or one of the other rods or processes, you always want to make sure your
weld is sound and that it looks good. The late Duane
McLaughlin used to tell everyone he met that "You're weld is you're signature!"
You always want to put down your best weld no matter what it is you're working
on. That means it should be tied into, or fused into the steel properly, and it
should have a good visual appearance.
To do that, you have to be using
the right tools, equipment, and rods. More and more home hobbyists are finding
out how good and versatile 7018 rods are. Heck, as a structural welder in the
Iron Worker's union, I used 7018 rods to weld shopping centers, factories, high-rise
office towers, power houses, dams, damn powerhouses (that's a joke) and virtually
every kind of structure out there. They are fantastic for mild steel and structural
Look at the many building projects listed at http://www.greatbuildings.com/types/construction/steel.html
and I'll bet you most were welded mainly with 7018 electrodes. Some of them may
have used flux core on column splices (where one column is stacked on another
at the splice that is bolted and welded solid) but I'd bet a pretty penny that
most of the other welding was with 7018. Of course some of the older buildings
used rivets but most of the modern structures use 7018 rods.
If 7018 rods
are good enough for a high-rise office tower, they're dang sure good enough for
most all of your hobby projects. Now I'm talking about relatively thick steel,
and 7018 rods are not good for welding open butt or grooves** or thin sheet.
***the correct technical name for rods are "electrodes".
But you will quickly find out I write on the non-technical style of the road!
In the shop or field they are called rods.***
**Open butt is two pieces
of plate with a space between them. Closed butt is the factory edge butted up
against the other factory edge. Grooves are plates that have been beveled to an
angle with a torch or grinder. This allows deep penetration of the weld.) A good
illustration can be found at http://www.unified-eng.com/scitech/weld/groove.html