Hydrocarbon flux & fluxless

[JTknives]

Thanks to Stacy who put this bug in my ear. I have been studying the process of using a hydrocarbon as a flux for welding. After I bit of reading its apparent that it works great but I started wondering why. So I dusted off the chemistry side of my brain and started researching. So let's see You grind the surfaces of the steel and stack. Then wire or welded the stack together. Then it gets a bath in a hydrocarbon "kerosene" bucket. Next into the forge to start heating up. The fuel will burn/decompose as it heats leaving carbon deposits on and between the layers. Now we come to the catchy part. It was said that the carbon acts as an oxygen barrier but I'm thinking it's more complicated then that and her's why. First off if carbon was just shealding the oxygen from the steel then we could have carbon trapped between the layers which would be visible on an etch. Next is looking at the carbon and the require forge atmosphere needed to make this process work. The fact that the forge is run with a reducing atmosphere which means there is more fuel then available oxygen is another clue. The next key is the carbon, in searching I found "The industry standard test for carbon content in graphite samples is to heat them to 1000C in a muffle furnace. At that temperature the graphite will burn off in a normal air environment". So carbon will burn at 1832° when in the presents of oxygen, so having a reducing atmosphere means we are not burning the carbon as it would in an oxidizing environment. So this got me looking at the actual numbers and it all made perfect sense. Your coating the surface with carbon and heating. In the forge your not building any scale because of the fuel rich environment. This environment keeps the carbon from burning off and alows it to become super heated to the tune of say 2300°. You pull the billet from the forge and the carbon is instantly exposed to oxygen rich environment which means it should burn. Now the linchpin to this entire operation lies in the production of iron. Iron is mined as ore which is iron oxide, basically the same stuff we are trying to prevent from foruming between the layers in the pre welded billet. So how is iron ore turned into steel, WITH CARBON. The entire process in a nut shell is this. Carbon is burned with oxygen at high temps creating not C02 but just C0. This Carbon monoxide passes across and through the iron oxide and once the iron oxide heats up the oxygen jumps ship and attaches to the carbon monoxide creating carbon dioxide leaving iron behind. This also seams to happen at 1000°c according to research. So what I think is happening is once the billet is pulled from the reducing forge environment into the oxygen rich air the carbon flashes and creates carbon monoxide which then reacts with the steels surface pulling out any and all available oxygen from any scale that might of just formed and quickly turns it back to iron. This means no carbon left between the layers and a very pure and clean surface to weld that's shelled with CO2. And the formula below spells it all out.

C2 + O2 ---> 2CO + heat
3CO + Fe2O3 + heat ----> 2Fe + 3CO2

What do you guys think, am I off my rocker and thinking to much into this?

Edit, my eyes where just opened with fluxless welding.

 

[Greenberg Woods]

One little thing you may be forgetting, is that carbon is highly soluble in iron at high temperatures. Ever wonder why you never see diamond grinding belts? Its because the carbon can dissolve in iron at high enough temperatures.

What I do know carbon is used for is in welding up cans of damascus, as carbon has a much higher electronegativity than iron, that is to say electron doners like oxygen are more likely to bind with it. Thats why when people weld up a can of damascus they will throw some paper or a little bit of gasoline into the can.

As a flux, I have heard of it but not put a ton of thought into it.

 

[jdm61]

Don't know exactly how it works, but it works like a charm. I was told that you need to be careful handling the billet out of the forge because you can "crack the shell"

 

[JTknives]

Also a little info, iron is used as a flux when making synthetic diamonds. Diamonds are very wear resistant except when it comes to iron. As a machinest we used diamond tipped boring bars and turning tools but not on iron based aloys. Cubic boron nitride was much better on iron.

From the research I did on foundry production thy said that solid carbon can dissolve into iron but it's very slow. The carbon (coke) is layered in the crucible with the iron oxide and ignited. Hot oxygen is blown in from the bottom and burns the carbon making carbon monoxide which when in contact with iron oxide robs the oxygen to make carbon dioxide.
Carbon dissolving into the surface is case hardening and takes hours just to go .001, the charts I have seen show .001-.002 after 2hrs and .008 takes 8-10hrs.

 

[Evan Miner]

The question I have is. Does this work for all hydrocarbon fuels. I've tried diesel. For me this seems to work pretty well for the small bullets I create. ( limited do to hand forging Damascus ) the main reason I'm asking is cause I work for a company that recycles solvents and all kinds of fuels so I have a wide variety of hydrocarbon based products. I understand that the use of any hydrocarbon isn't safe and should be done in well ventilated areas and really shouldn't be breathed.

 

[JTknives]

I don't know but a guess would be most hydrocarbon is ok, just need to be woried what is left behind with the carbon. I think that's why kerosene is popular, it's a pure hydrocarbon. If there is junk left with the carbon I think it will give you problems.

 

[Alpha Knife Supply]

Why use flux? You live in Washington state now. Ask a local knifemaker to teach you to dry weld.

IMO, dry welding results in the best looking damascus.

Chuck

 

[jdm61]

IIRC, Chris Marks uses diesel. I just buy a gallon of kerosene in the paint department at HD of Lowes and transfer it to a 1 gallon steel paint can. Some guys swear by a particular type of tool cleaner solvent that Tractor Supply carries....sometimes. I was never able to find it locally

The question I have is. Does this work for all hydrocarbon fuels. I've tried diesel. For me this seems to work pretty well for the small bullets I create. ( limited do to hand forging Damascus ) the main reason I'm asking is cause I work for a company that recycles solvents and all kinds of fuels so I have a wide variety of hydrocarbon based products. I understand that the use of any hydrocarbon isn't safe and should be done in well ventilated areas and really shouldn't be breathed.

 

[JTknives]

Ok chuck why did you have to do that, I read that and just about ran to the door. wife is like where you going it's midnight, to the forge to trying somthing that's impossible. Well fired up the forge and grabbed the closest metal which was a strip of 15n20 and cut off a small chunk and hit the mating sides with a scotch bright wheel to clean of any grim or rust. Set the small square on the end of the bar and placed in the forge. Once it was butter yellow I pulled out and slipped into the press. Hum I say it did not fall off, can it be, no way. Then back into the forge and once butter out it came and tap tap with the hammer. Back in e forge and then back out and hammered over the edge and bent over. HOLY CRAP IT WORKED, no way. Off to the grinder to grind the sides. Wife walked in and I'm standing dumbfounded at the grinder. I polished one side to a mirror polish and then etched both sides. When polished or ground you could not see any line. When I etched you could see the weld line as slightly lighter in color. I am just shocked, this is not sapost to work, we must use flux we must. I snapped some pictures so show anyone that might be thinking I'm as crazy as I feel.

 

[Stacy E. Apelt - Bladesmith]

One little thing you may be forgetting, is that carbon is highly soluble in iron at high temperatures. Ever wonder why you never see diamond grinding belts? Its because the carbon can dissolve in iron at high enough temperatures.
What I do know carbon is used for is in welding up cans of damascus, as carbon has a much higher electronegativity than iron, that is to say electron doners like oxygen are more likely to bind with it. Thats why when people weld up a can of damascus they will throw some paper or a little bit of gasoline into the can.

As a flux, I have heard of it but not put a ton of thought into it.

This is the silliest thing I ever saw posted by a college student. Go talk to one of your material science or chemistry professors.

Carbon burns turns into carbon dioxide (in the pre3sence of sufficient oxygen ... like air) at 1250°F. If you heat a diamond red hot, it will slowly "burn" away. There are many diamond grinding belts, and most major sellers carry them ... the diamond bort ( small crystals) does not dissolve into the iron