Quick question: Understanding that 7018 should be fresh/dry to meet its design characteristics, will it perform at least as well as 6013/6010 etc if stored in an open, but ambient air setting?
Thank you.
Ken
I think the next question is what are you planning to weld? Also, how long have they been out? hours? days? weeks? months? years? where are you located? Humid Florida or dry Arizona?
If it is any structural or pressure applications requiring code quality, I would not recommend it. If it is any form of non-critical welding (home, ornamental, etc.), you may get away with it. Seen it done but Florida's humid moisture can destroy flux shielding.
Ken,
Ill take a shot at this. From what I understand its not the performance of the rod that is afected its the soundness of the weld.
A 7018 rod that is contamenated by moisture (in the air) will contamenate the weld with carbon pockets (carbon percipitation), I think its called. Which will make the weld weak. And undependable.
I think underbead cracking, caused by hydrogen embrittlement is the technical term.
Anywho just to see what happens I welded up a couple test coupons in the 6g position with A106 grB seamless carbon pipe 3" std, using 7018 root fill and cap, no preheat, outside temp 5 deg F. These rods have been out in my garage for 2 yrs on a cold steel bench in southern Ontario where we often get, humidity readings up to and including 100%.
I did cheat a little by grounding the rods to "bake" the moisture out each time I used a new rod. I'd stop "baking" them as soon as the steam stopped forming from the rod.
Cut the coupons,cleaned them up and bent them in our shop guided bend tester,they all passed,all ROOT bends I might add.
Got lucky, although sometimes in real world applications things don't happen as they do in the book, had this test been done on heavier wall pipe with more passes, no preheat and the lack of "baking" the rods the way I did, it may have been a different story.
Skip
Hey Skip,
That's cool the way you took the time to do a physical test.
It's amazing sometimes the way welded objects refuse to come apart no matter what. It seems like ever since I became a welding Inspector, I notice welded structures, other than at work, a lot more. I often see a lot of scary looking stuff out there that looks like it was done all wrong , or only partly done, yet it's been there, holding it's own, for years.
Many times I've run across stuff that has only been tacked together, where it looks like someone forgot to weld it, yet it's still there, holding more than it should.
I guess the big difference that governs how something is to be assembled and welded is whether or not expensive equipment and / or innocent lives are at stake.
Tim
The coating on low hydrogen welding consumables will degrade over time in a moisture containing environment, but it will take a while. If it still welds adequately, then it shouldn't give out more hydrogen than 6010 rod, which contains about 5% moisture in the coating in order to make it run correctly. A low hydrogen rod that has absorbed moisture from the atmosphere will be less than 5%.
Texarc,
The exposure doesn't have anything to do with carbon, only hydrogen. Too much hydrogen can cause cracking/brittleness and porosity.
GROBERTS
hydrogen, I understand thx for the correction. also took a closer look at the term carbon percipitation sorry for being so far off on that one
One of the main things to watch out for with using moisture contaminated 7018 rods is called under-bead cracking.
These cracks normally lie parallel with surface of the bead, along the root. Therefore, they are most often not visible from the surface. As with most any crack, it is likely to propagate and result in failure of the weldment. That's why the codes are so strict about LH rod storage.
Ultrasonic Testing is useful for exposing under-bead cracking. Liquid penetrant won't find it unless the crack as already propagated to the surface. Radiography may not identify it, as the crack most will most likely be parallel with the surface.
One thing to consider is that if the flux is not damaged, the rods may be re-baked in order to eliminate the moisture contamination.
See this chart for exposure limitations and re-baking parameters.
http://www.metalsmith.org/edu/materials/weldrodstore.html
Be safe,
Tim
Appreciate everyones reply.
My application is just making some simple, non-critical welds for some simple stands to hold a grinder etc. I had a pound of 7018 that was in a sealed plastic bag from the welding supply store rather than in an orginal sealed container from the mfgr. I'm was just wondering if something stored that way would be no "worse" than dry 6010 or the like. I live in the Sierra mountains at about the 3100 foot level and keep the electrodes in plastic bags/containers. If I needed to make a critical weld with 7018, I would certainly use electrodes from a fresh pkg or properly baked according to specs.
I found the idea of grounding the electrode to "bake" it an interesting approach. I seem to do that alot inadventently. Never could cook, end up burning them half the time.
Thanks again for the replies.
Ken
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