why "low hydrogen"

[arrow]

I split my wedge off of the splitter so now I have to re-weld it back on. The splitter came from Northern 16 years ago but I am assume they used their own splitting wedge when they built this one. At any rate, they call for a "low hydrogen" rod to weld their wedges on. Low hydrogen to me means a 7018 rod. Curious as to why a 3/4" thick piece of metal or any thickness for that matter needs low hydrogen otherwise is there an important reason why I cannot use 6011 for the root and 7014 for the fillets?.

 

[Gary Fowler]

The wedge should be hardened steel and 60xx rods are not ductile enough to use. The weld on to hardened steel will be way too susceptible to cracking. LH rods in the as welded condition are very ductile and much higher tensile strength than the 6011. I have never seen a 7014 rod with the weld characteristics to hold a thick piece of steel. A couple hits with a hammer will snap them off even with 2 or more passes. Save yourself some rework time and get some 7018 or even 8018 to weld it back with and "do it once-do it right".

 

[arrow]

The wedge should be hardened steel and 60xx rods are not ductile enough to use. The weld on to hardened steel will be way too susceptible to cracking. LH rods in the as welded condition are very ductile and much higher tensile strength than the 6011. I have never seen a 7014 rod with the weld characteristics to hold a thick piece of steel. A couple hits with a hammer will snap them off even with 2 or more passes. Save yourself some rework time and get some 7018 or even 8018 to weld it back with and "do it once-do it right".

Good enough Gary, Thanks

 

[dstig1]

The problem is called hydrogen embrittlement. Hydrogen is a very small molecule/atom, and so it tends to get into very tiny spaces that other things won't be able to fit into. In this case, it is the grain boundaries between the grains in the steels that form as it cools. As the Hydrogen reform into H2 molecules, it expands and causes trouble. They cause weakness and make the steel fail at much lower forces than it normally would. Only really happens when the steel is hot enough to be molten or near molten, which is the perfect description of welding. Low hydrogen rods mainly mean lack of water, as that is the primary source of hydrogen in welding. That is why you have to keep them in an oven to dry, so they don't absorb water.

Wiki link if you are curious

Hydrogen embrittlement - Wikipedia, the free encyclopedia

 

[arrow]

Thanks dstig for the more technical explanation making perfect sense. I welded it back up using the Tractor supplies' Hobart E7018. It is no wonder the 7018 is a almost everyone's go to rod as it is just about idiot proof. Best welds I've made and I stink at welding. There was a bit of an undercut on the 1/8th rod at 115* on my inverter welder but I think I was going a bit slow. Anything less temp wise seemed to stick the rod. At any rate I'm glad I bought a bunch. Thanks Gary for the gentle lead.

 

[BukitCase]

If you "bought a bunch" of 7018, you might want to get one of these for each size you have -

Welding Rod Keeper

Put ALL the rod in those BEFORE they draw dampness and KEEP it there, tightly closed - otherwise, you'd be better off just buying a few sticks as you use it.

Lo Hy rod is the only kind this is really necessary for, and if it gets wet it can (sorta) be "rejuvenated", but it takes a hot oven and several HOURS to do - if it's KEPT dry, that can be done as simply as these cannisters or a small refrigerator repurposed as a "dry box" - a light bulb inside and a small vent hole in the top works pretty good... Steve

(If you're doing Xray quality welds, ignore all this and do what the inspector says

 

[arrow]

If you "bought a bunch" of 7018, you might want to get one of these for each size you have -

Welding Rod Keeper

Put ALL the rod in those BEFORE they draw dampness and KEEP it there, tightly closed - otherwise, you'd be better off just buying a few sticks as you use it.



Lo Hy rod is the only kind this is really necessary for, and if it gets wet it can (sorta) be "rejuvenated", but it takes a hot oven and several HOURS to do - if it's KEPT dry, that can be done as simply as these cannisters or a small refrigerator repurposed as a "dry box" - a light bulb inside and a small vent hole in the top works pretty good... Steve

(If you're doing Xray quality welds, ignore all this and do what the inspector says

Thanks Bukit. This case you're showing me seems a lot handier as you just unscrew the lid when you need rods. Much easier than what I was going to do when I thought to simply tape up the seam of the plastic case the rods came in. Someone wanting me to do xray quality welds is akin to me taking out your appendix. You wouldn't want me for that either even if I am cheaper than most docs. You would be on an outpatient basis however as we go out for pizza after most surgeries done in sterile environment of the garage.

 

[Big Barn]

If you "bought a bunch" of 7018, you might want to get one of these for each size you have - Welding Rod Keeper Put ALL the rod in those BEFORE they draw dampness and KEEP it there, tightly closed - otherwise, you'd be better off just buying a few sticks as you use it. Lo Hy rod is the only kind this is really necessary for, and if it gets wet it can (sorta) be "rejuvenated", but it takes a hot oven and several HOURS to do - if it's KEPT dry, that can be done as simply as these cannisters or a small refrigerator repurposed as a "dry box" - a light bulb inside and a small vent hole in the top works pretty good... Steve (If you're doing Xray quality welds, ignore all this and do what the inspector says

In addition to what Steve said, these portable ovens set at 300 degrees come up for sale used quite often. I am relatively new to 7018 but they run 'sooooo' nice right out of the oven.



Terry

 

[bigdeano]

You might want to put a desiccant packet in those rod storage tubes if you're going to keep the rods a long time. Air and other gasses go thru plastic over time.

 

[arrow]

You might want to put a desiccant packet in those rod storage tubes if you're going to keep the rods a long time. Air and other gasses go thru plastic over time.

Good idea Bigd

 

[muddstopper]

I keep my rods in one of those canisters. Anytime I know i am going to have a bunch of welding to do, I take my rods out of the canister and place them on top of the wood stove. Leave them overnite and they will weld like new. works good in thw winter hen I have a fire in the stove, not so much in July and August. I have been thinking about getting one of those little dorm fridgerators and installing a 100W light bulb and using that for a rod oven.

 

[MinnesotaDaveChalmers]

I keep my rods in one of those canisters. Anytime I know i am going to have a bunch of welding to do, I take my rods out of the canister and place them on top of the wood stove. Leave them overnite and they will weld like new. works good in thw winter hen I have a fire in the stove, not so much in July and August. I have been thinking about getting one of those little dorm fridgerators and installing a 100W light bulb and using that for a rod oven.

A lot of people do this with the little refrigerators - the rod ovens sell really cheap used so you may end up wanting that instead.

The 50lb rod oven I started using is 150 watts but has a thermostat so it doesn't use as much power as those that run all the time.
It was $100 including shipping and had the little dividers in it already.

I was a late convert to 7018, but I eventually, begrudgingly, switched over from 7014 to them - I don't like to change... :laughing:

 

[Gary Fowler]

The refrigerator with light bulb works OK for cellulose fluxed rods like the 6010/6011 but it doesn't get hot enough to keep moisture out or remove it once absorbed in low hydrogen rods. The 50# boxes and even 10# ovens from Phoenix dryrod keep them at 300F and are well insulated so the heating element doesn't run much of the time so it is much cheaper in the long run to put the money into a drybox oven and save on electrical cost PLUS have them at the right temps and always dry which will save you from having a bunch of rods go bad (bad as in wont weld without pin holes ).
I found a good 300# one on Craigslist many years ago for $150 and keep all my LH rods in it and it on full time. Most of the time, my shop electric bill (separate meter from the house) is just the minimum amount so it isn't really costing me anything to run it.
I see the 50# size occasionally for as little as $50 so not a lot of money invested to be able to keep your electrodes protected.

 

[muddstopper]

Dave, I have built several chicken egg incubators over the years. I like these wafer thermostats pretty well. Thermostat - 59S | Incubator Parts | Chicks and Game Birds from Stromberg's |. I think somthing like this would work well for a rod oven using a bulb as a heating element. I have also bought the resistance wire and made my own heating elements, 15M Length 1 6mm AWG14 Gauge Kanthal A1 Resistance Heating Coils Resistor Wire | eBay. Use a couple of porcelan electric fence insultors and wrap the wire around them, hook to a thermostat , add a computer fan, and presto, instant heater.

 

[buickanddeere]

Rod oven or go home

 

[arrow]

The refrigerator with light bulb works OK for cellulose fluxed rods like the 6010/6011 but it doesn't get hot enough to keep moisture out or remove it once absorbed in low hydrogen rods. The 50# boxes and even 10# ovens from Phoenix dryrod keep them at 300F and are well insulated so the heating element doesn't run much of the time so it is much cheaper in the long run to put the money into a drybox oven and save on electrical cost PLUS have them at the right temps and always dry which will save you from having a bunch of rods go bad (bad as in wont weld without pin holes ).
I found a good 300# one on Craigslist many years ago for $150 and keep all my LH rods in it and it on full time. Most of the time, my shop electric bill (separate meter from the house) is just the minimum amount so it isn't really costing me anything to run it.
I see the 50# size occasionally for as little as $50 so not a lot of money invested to be able to keep your electrodes protected.

I don't weld on a regular basis. Maybe 5 or 6 times per year depending on the project. If I am to understand this, one , foreseeing a welding project the next day, takes out the amount of rods being used that day and places them into a 300* environment for 6 to 8 hours. Or...do the 7018's need this environment on a constant basis? If so, according to Buickanddeere, I'm going home as I refuse to burn up 109 kilowatts per month to keep a rod oven going constantly. Even using 60 kilowatts per month costs over $8 here. For a guy who welds as little as I do, I'm hoping the former part of my understanding on how one might use a rod oven indeed suffices.

 

[buickanddeere]

The rod oven does not run 24/7. In the winter it does heat to the shop so no loss there. b.t.w. why are you blaming me ?

 

[aczlan]

b.t.w. why are you blaming me ?

I suspect its in response to this post:

Rod oven or go home

He is saying that he doesn't weld enough to make it worth running a rod oven...

Aaron Z

 

[muddstopper]

The goal of having a rod oven is to keep the rods dry, not keep them hot. A thermostat controlled heater will keep the rods dry, will even dry out wet rods over time. Maybe not as quick as a 300* rod oven. With rods that have been exposed to the atmosphere and absorbed moisture, High heat for a few hours will dry them out for immediate use, but rods that just need to be kept dry dont need 300* degrees to stay that way. A Christmas tree light will provide enough heat in a small area to keep a few lbs of rods dry with out spinning the electric meter off the wall

 

[bigdeano]

7018 that has absorbed moisture needs to be heated to 800F to be dried out. Apparently the water combines chemically with the rod coating, it's not just a matter of evaporating it. I read it on the Miller website I think. I tried 450F for three hours but it didn't seem to do anything for my old 7018 rods.

If I need to weld high carbon steel I use 308L stainless. It's twice as ductile as 7018.