Need Help Forge Welding

[Jerrod Miller]

16 minutes ago, owen bush said:

I weld with anhydrous borax and it still displays this phenomenon, in my experience the bubbling is more vigerous in a rich environment than it is in an oxidising one. to the extent that I would change my gas mix if there was no bubbling. when I weld with borax I look for the "kids running around in a playground" vigourous bubbling that has been mentioned and that the borax is smoking. The colour of the steel is so subjective.....

Mildly off topic, but I find this extremely interesting.  Thanks for sharing Owen.  

[Joshua States]

On 2/27/2017 at 4:51 PM, Joe kemp said:

 

Here's what ive got as a result. These are just some pieces I have cut out of the overall piece. 

Owen's post got me thinking about heat and forge environment. I went back and looked at Joe's photo and thought that it looked like the pieces had oxidized heavily in the forge. Could the problem with this forge weld be one of forge environment rather than one of temperature control?

[Alan Longmire]

I don't think that's oxidation, it looks like wood tar.  The fact that there is some blue temper on one end and shiny unheated steel in the middle leads me to that conclusion.  Joe, can you scrape that black stuff off, or is it part of the surface?

[Joe kemp]

On 3/1/2017 at 5:23 PM, Alan Longmire said:

I don't think that's oxidation, it looks like wood tar.  The fact that there is some blue temper on one end and shiny unheated steel in the middle leads me to that conclusion.  Joe, can you scrape that black stuff off, or is it part of the surface?

Yes that black stuff flakes right off. It is in no way stuck to the metal or I should say it doesn't appear to be the metal flaking. I do believe it is wood far as you said. I just picked up some hardwood charcoal with no added chemicals from the store today and while working on my machete project I did realize that the metal was getting much much hotter than it was with wood. I am also planning on lining my forge with fire clay mortar to contain more of the heat than the forge does now, is this a good idea and will it work? My goal is to make knives fairly cheap so I am using slot of materials I already have access to at my house and one of them are some old fence stakes I pulled out of my back yard. Sparked checked and they appear to be in a high carbon range. The pieces I tried to forge weld are from those stakes. My plan is to turn these stakes into a Damascus steel knife, does anyone think that this will actually work? Or should I just buy some 15n20? I was already planning on buying some 1095 or 1085 to use on other knives so they come out nice and I can harden them properly, does any one know of some good suppliers I can buy some billets from for fairly cheap?

[Joshua States]

It is highly unlikely that fence stakes are high carbon steel. You could try forge welding them together and use it as a jacket around a piece of tool steel San Mai style. Remember that mild steel requires higher weld temps than tool steel.

[Alan Longmire]

Those T-section posts are hardenable, and they are very tough, but there's no telling what alloy or how best to treat them besides experimenation.  If you're going to work with scrap, be prepared to experiment a lot.  As in every piece.  Once you learn how to read a spark trail (this takes more experience than you'd think) you can ballpark the carbon content.  Doesn't help much with alloying elements in most home-forgeable steels, though.  Then you have to learn to heat treat each item since they're all different.  

I'm certainly not saying you can't do it!  I am saying if you want to learn how blade steels behave start with known materials, the learning curve is much shorter and we can help with heat treat questions and so on.  Once you have learned how different steels behave, then by all means set off into the unknown, but with the knowledge you are on your own when it comes to the technical stuff.

[Kevin Colwell]

yes, and there should be a LOT of fuming when you pull a borax-coated billet from the forge. That fuming is a great measure/indicator.

I agree with Owen on the atmosphere as it relates to borax behavior at temp. I was going to type it but he beat me to it.

 

Fast. Move fast. Steady and quickly to the anvil and to strike the firm blows. Strike and push a bit rather than just letting the hammer bounce.

 

If you have steel with a lot of nickel, borax won't work on nickel oxides once they are formed, so that may be part of it. Try hot and clean, first.

[Alan Longmire]

Forgot to add earlier in response to the blue oxide and wood tar on shiny steel from the middle of the billet:  be sure to let the whole thing come up to heat.  The wood tar indicates you didn't get anywhere near hot enough to forge, much less weld.  If the blue was just there and did not come from grinding or tack welding, that means the center of your billet was too cold by around 1800 degrees F or more.  

[JJ Simon]

I'll add an interesting thing I learned from Roman Landis.
In a coal forge without having to pull the work piece to check if it is at welding temp.
The flame will turn from lemon yellow to gold.
I don't know why.
I can only assume a chemical reaction.
But every time I pulled the piece after that it was at welding temp.

I don't know if charcoal will do the same thing.
I think we should point out that a reducing atmosphere is needed for consistent welding.
If you have an air blast hitting your work in a coal or charcoal forge that is going to cause problems.
If you have to lean an atmosphere in a gas forge it will also cause problems.

[Joe kemp]

Yes so I reference to Alan I believe the blue tempering we as from cutting the pieces apart and also I do believe that the metal wasn't near hot enough to weld. In reference to JJ I'm actually interested in that notion of the changing color of flame from yellow I think I may have an inquiry into why that changes from my background in chemistry. Now you said that you were told that when the flame turns gold the metal is ready to forge weld. If I apply my knowledge of chemistry we can find out that the flame color of iron (Fe) is actually gold. This flame color would only occur when the iron in the steel is reaching its spontaneous oxidation state or ignition temperature. If this steel, I assuming carbon steel, which is not only iron is igniting the iron in the steel is physically bonding with the oxygen atoms forming iron oxide. This reaction is rapidly pulling iron atoms away from the surface of the steel and causing an AB+C=AC+B reaction where the iron atoms bonded with the carbon are releasing the carbon atoms for a more stable bond with the oxygen atoms. I would also like to ask if at the same time of this gold flame are sparks seen coming out of the fire in a sparkling fashion similar to that of the spark off a carbon steel on a grinder, because these sparks would indicate the released carbon atoms from the ignition reaction. Another reason why I believe this is the case is that they say you want to have your steel just before melting for it to be ready for an effective forge weld and this high temperature would be the perfect environment for the ignition steel giving off the gold flame and sparks as well.

[S. Cruse]

Joe, just to clarify, is the steel outgassing Iron to cause the glow, or is the wood outgassing and being ignited by the residual heat on the steel? I know there is a way to convert wood into fuel for an internal combustion engine, Similar Process maybe?

Edited March 4, 2017 by S. Cruse

[Kevin Colwell]

having a steel spark fly out the front of a gas forge every now and then (the type that bursts when it hits the oxygen outside the forge) is a good sign that you are ready to weld. So, you may be on to something with the more iron oxide in the exhaust gas. (I was a chemistry student, once, too).

 

So, aim to have the stack just below the point that it begins to sparkle or crumble, in an oxygen-poor environment, and you are at the right point.

You CAN weld colder (Cashen does, Fogg doesn't), but there is no NEED to weld colder and it is easier when you have  )it hotter. When you try O1 you have to work colder (Cashen uses it), but with simpler steels there is no local depression of melting point due to alloy concentrations, and so no danger of the steel melting in some places at relatively lower temps and falling apart on you like brass does when you heat it (for the same reason).

 

 

kc

Edited March 4, 2017 by Kevin (The Professor)

[Alan Longmire]

Working in coal as I do, I notice the flame turn what I see as light green at welding heat as long as I am using borax. If I am doing a lot of welding, once enough borax gets in the fire the color change no longer helps because it's always green.  This suggests to me it's the flux and not the steel.  You really don't want the steel dissociating in the fire, after all.  

[JJ Simon]

13 hours ago, Joe kemp said:

Yes so I reference to Alan I believe the blue tempering we as from cutting the pieces apart and also I do believe that the metal wasn't near hot enough to weld. In reference to JJ I'm actually interested in that notion of the changing color of flame from yellow I think I may have an inquiry into why that changes from my background in chemistry. Now you said that you were told that when the flame turns gold the metal is ready to forge weld. If I apply my knowledge of chemistry we can find out that the flame color of iron (Fe) is actually gold. This flame color would only occur when the iron in the steel is reaching its spontaneous oxidation state or ignition temperature. If this steel, I assuming carbon steel, which is not only iron is igniting the iron in the steel is physically bonding with the oxygen atoms forming iron oxide. This reaction is rapidly pulling iron atoms away from the surface of the steel and causing an AB+C=AC+B reaction where the iron atoms bonded with the carbon are releasing the carbon atoms for a more stable bond with the oxygen atoms. I would also like to ask if at the same time of this gold flame are sparks seen coming out of the fire in a sparkling fashion similar to that of the spark off a carbon steel on a grinder, because these sparks would indicate the released carbon atoms from the ignition reaction. Another reason why I believe this is the case is that they say you want to have your steel just before melting for it to be ready for an effective forge weld and this high temperature would be the perfect environment for the ignition steel giving off the gold flame and sparks as well.

In my limited experience, the flame turns gold before sparks start coming out of the coal.
As far as I understand it, sparks happen when you have begun to burn the carbon out of the steel.
The higher the carbon, the lower the temp.
So to weld wrought to wrought or iron to iron you need more heat.
So much so, some gas forges won't do it.
Where as, high carbon welds at lower temps.
You can dry weld in a gas forge.
It has to be really rich.
I have no idea if this can be done in a coal forge.
I have done it in gas never in coal.

[Joe kemp]

I reference to S. cruse I think what your asking is that the heat from the is causing the wood to burn and produce a different color flame. However this color produced is actually the color of the steel burning. As we all know as you heat steel the hotter it gets the more scale or oxide is produced but once steel reaches it ignition temperature the oxide would no longer stick to the surface of the steel but it would fly off the steel and to the best of my understanding it would carry away the carbon in the steel as well and once it hits the oxygen rich environment outside of the fire which burn most of the oxygen within the area where the steel is placed the carbon sparks in a reaction with the oxygen as the carbon is in an unstable state and would consequently produce CO2 as it reacted to become stable. The result of this reaction would be the co2, as well as light, as seen in the sparks, as well as heat which propells the flowering sparks in different direction, as most of us probably know, due to the indifference in pressure cause by the uneven heating of air around the carbon reaction. Also the gassifier system you a talking about is done by heating wood in a closed environment therefore starving it of oxygen which then heat the vaporizes the liquids in the wood which are combustible and can be used for a combustion engine. Charcoal is also produced as a result from removing these substances from the wood leaving a carbon rich compound.

23 hours ago, S. Cruse said:

Joe, just to clarify, is the steel outgassing Iron to cause the glow, or is the wood outgassing and being ignited by the residual heat on the steel? I know there is a way to convert wood into fuel for an internal combustion engine, Similar Process maybe?

 

[Joe kemp]

14 hours ago, Alan Longmire said:

Working in coal as I do, I notice the flame turn what I see as light green at welding heat as long as I am using borax. If I am doing a lot of welding, once enough borax gets in the fire the color change no longer helps because it's always green.  This suggests to me it's the flux and not the steel.  You really don't want the steel dissociating in the fire, after all.  

Now as I have come to find out the color of borax reacting with water in the air is green and yields the two compounds sodium metaborate and boron oxide. While the boiling point of borax is 2867 degrees F it highly unlikely that the borax is boiling but is possible that some of borax is steaming off, as previously stated that it is steaming when removed from the fire, similar to how water might be steaming when heated but not boiling. This vaporized borax is then reacting with water vapor in the air I can assume comes from the air being forced into the forge.

[Joe kemp]

to extend on my previous comment i should also mention that the twenty mule team borax is actually a hydrated version of the molecule making it sodium tetraborate decahydrate. my comment on this could be that the water is being freed of the molecule and then under the heated conditions in the forge may be reacting with the sodium tetraborate molecule. I don't know this could have anything to do with this phenomenon but just something to think about.

[Alan Longmire]

Yes, but I use anhydrous sodium tetraborate and it still turns green.    Don't overthink this stuff, just use it to learn to weld.

[Gerald Boggs]

30 minutes ago, Alan Longmire said:

Don't overthink this stuff, just use it to learn to weld.

Noooo!! must make everything harder then it is :-)

[Jan Ysselstein]

Your best bet is to find someone in your area and have them show you in person. I went through some of this  ( we all probably did ), then I built a crucible furnace and found out what hot really is is...after that no problem  borax.

[Gerald Boggs]

Not me, I hanged myself from a tree and gained all blacksmith knowledge.

[Alan Longmire]

Not all, you still have both eyes!

 

Seriously though, while it is theoretically possible to achieve a solid state diffusion bond (aka a forge weld) at room temperature with microscopically flat and chemically clean surfaces in a vacuum, for what we do we use heat of around 2200-2400 degrees F (higher carbon needs lower end of the range, lower carbon needs higher heat), a way of preventing or removing surface oxides (flux or reducing atmosphere), and pressure to encourage the bond to form, which can be a hammer or a press.  If you have these three things in place throughout the whole billet you will achieve a weld.  Assuming of course you chose steels that will in fact weld in a forge.  Chromium and nickel form tough oxides that do not dissolve easily, which is why stainless and some spring steels don't like to stick to each other in an open forge environment.

 

That said, I repeat that based on your picture the center of your billet was around 1500 degrees F too cold.  You didn't excite your electrons sufficiently to achieve a bond.  Practice the heat by burning some steel in the forge.  You want to weld right before it turns into a sparkler.  After it turns into a sparkler is too late. Permanently.  It just takes practice, and yes, watching it done is very helpful.  Sacrificing an eye to a dwarf at the spring of knowledge and self-crucifiction for nine days may get you wisdom of the world, but unless said tree has a view of a blacksmith shop you're not likely to learn forge skills that way.

[Joe kemp]

Thanks, all this was indeed very helpful in my endeavors to make my own knives start to finish and I will hopefully be getting some coal here very soon so I will be able to start making some forge welds. And if I can't figure it out I will try to find someone willing to teach my stubborn ass (I don't like to listen and I like to try and figure everything out on my own until I have come to an extreme point of defeat in which I will hang my head in shame and seek help).