First forge weld/Fire poker attempt

[ThomasPowers]

Have you read "Solid Phase Welding of Metals", Tylecote?  Also I've discussed explosive welding with the Energetic Materials Research and Training Center at NM Tech; we hear their blasts on a regular basis at my house.  There is a lot of explosive art on the NM Tech campus with explosive welding of dissimilar metals and or explosive repousse.

I generally explain Solid Phase Welding as a 3 legged stool; cleanliness, pressure, temperature  Max out any one and you can get a solid phase weld:

Cleanliness: vacuum welding

Pressure: galling or explosive welding

Temperature: forge welding

Mixing them helps to get welds when not at the extremes.

[Sly]

are we talking about getting a weld or keeping it/improving it though.

[ThomasPowers]

In my experience it's the welds you didn't plan on that seem to hold the most tenaciously!

When I was working on some 2.5" sq stock up above 7000' in a propane forge, another smith repositioned their 3/4" round stock and slid it along my piece and it welded solid at the contact point---had to use a sledge hammer to get it off. No flux, no hammering and a very good weld!

[Pr3ssure]

All very interesting stuff. I'll have to look into all of it. I haven't been able to forge in a few days, have other stuff I need to get done. The snow put me out of doing anything today though. Was just too cold, considering it was 65 degrees yesterday and down to 30 today.

[Sly]

6 hours ago, ThomasPowers said:

In my experience it's the welds you didn't plan on that seem to hold the most tenaciously!

When I was working on some 2.5" sq stock up above 7000' in a propane forge, another smith repositioned their 3/4" round stock and slid it along my piece and it welded solid at the contact point---had to use a sledge hammer to get it off. No flux, no hammering and a very good weld!

How you think blooms are made? it comes from the grains expanding and then the small grains dissolve and reform into larger ones.

theres no "weld lines" in bloom steel either.

I had a few layers of Cru Forge V and W2 that would NOT weld together no matter what I did to it, so I just soaked the stack for two hours and let it cool and it came out perfectly solid without hitting it any more. (I still did about three passes on it to be sure though)

[4elements]

Sly said 

"Welding temp can be anything above half it's melting temp. but low carb steels wont weld without the high heat. higher the carbon content the easier it sticks. its also important for the welded parts to be in the same phase state and relatively same temp. 

another trick is do a prolonged soak time in between welds to allow the steel to weld to itself from grain growth. but clean surfaces are a must, it takes a VERY long time soaking for the steel to absorb any content that gets stuck inside of it. "

So I am curious if someone had a cast iron ASO with a clean flat face, and a plate of carbon steel to match it, if they were put into a furnace, say a pottery kiln, and soaked at some elevated temp would you expect an acceptable weld to form across the entire face?

[Sly]

Erg. Its kind of like when a noobie tries to heat a knife using a magnet to find the non magnetic point and then quench it. Ok great your temperature is when austenite "forms" which is like 10% austenite. to really get 100% austenite with something like O1 as an example you would have to heat it for half an hour at 1600, or less time with a higher heat. the phase state as well as even temp matters for welding too regardless of the metal. 

low carb steel is the same thing, the higher heat just achieves the desire state, but you can get there with a simple soak time without the need for the sparklers. the halfway to melting temp is sort of like a midlife crisis of transformations for steels. I weld low carb steel to stuff all the time at orange colors and flux without issue, I even make my own wrought iron sometimes just forge welding wire together with thin sheets of 1018 for blade cores. Not once have I ever had to make a sparkler.

I trolled my local abana friends by austenizing a 15n20/1095 billet at a high orange temp with a long soak time, let it cool to cherry red and then cleaned it closed the fold and welded it almost grey in daylight and it took just fine, the reason it COULD do that is that when you have a complete transformation it takes time to dissolve, it just doesnt magically convert when you reach a temp. (even though its a really low temp its still austenite because it takes time to convert and still forgable lol). 

Heating it to sparkler welding temp you have enough heat to get a significant transformation but it isnt required, it is however more convenient then a soak time. but if it fails you didnt get enough soak time usually.

the real issue is do you want to simply burn your steel up potentially doing a partial liquid state, or do you want to be patient and not waste metal.

 

[Pr3ssure]

So what I'm getting from some of the posts is that soaking the steel, especially mild steel, helps with the welding process? I was un aware of most of what's been said after my last post. It's all interesting but very confusing. I'm going to have to make a list of the points that have been covered here and research them all in more depth so I can better understand. I know of other types of welding but mainly friction welding. I've never heard of with soaking the metal it will eventually just weld on its own. If that's even what's being said.

Thank you all for the information on all these processes. As I knew, I have a lot to learn still but now it seems I have A LOT more to learn.

[Sly]

It is but there are conditions that have to be met to acheive it, heat over time isnt welding but integration so there is no weld.

Bloomery is one thing to look up it will change how you understand steel. The second is hot rolling.

I use a method of forge welding three outside seams, breifly reheat, then i pop the gap open with a chisel fill it with flux and then heat the part with the gap facing up till it liquidizes entirely. Then i forge from the end of the seam to squish the flux out like slowly stitching a seam.back and forth untill the impurities are worked out. 

So theres no gaps in the steel. Then it gets a very long soak time to do the fusion to erase the welds It has to be done in a ogygen free enviroment. You can do this with a reducing atmosphere or.you can paint it in satanite or clay, your steel cant burn without air, it.doesnt help to have a little carbon in there too to burn out any air.