Mike,

I get what you are saying about not taking chances. As a full time maker, like you, losses from problems are just too expensive. I admit that I have gone to extremes of preparing forge welds to minimize the risk of losing a billet, or blade. I consider the time spend prepping for a weld is time saved in losing billets. I also use my trip-hammer for setting welds. Mostly just a matter of what I am familiar and comfortable with.

My interest in this topic, is because of some work that I have done recently. With what I am doing, the pieces are forged into position and must be welded where they wind up. The scaling from forging them into position cannot easily be cleaned and there is no way to access the weld area to modify it. Having liquefied flux and scale within these areas is obviously problematic. So, I am interested in finding a "best practices" process for closing these welds. If they can be welded soundly without the use of flux, that may be the best solution.

I have seen videos of Japanese sword smiths forging bloomery steel into a solid mass. All of the voids in this spongy material were closed up without the use of flux. In the next step in preparing the steel for the blades, they stacked broken pieces of steel on what was described as an "iron paddle". These pieces are then forged welded together. It would scare the crap out of me to have to close all of the voids in such a mess. They did not use flux, but covered the stack of steel pieces with rice paper. The rice paper was covered with a thin clay slurry, then some type of ashes. Certainly, the clay worked to protect the steel from the atmosphere of the forge. But, it could only last until the first blows of the hammer. Just seems to me that there is something to learn here.

Below is one of the videos that I have seen. The interesting forge welding part starts at around 15 minutes.

[media] http://www.youtube.com/watch?v=VE_4zHNcieM [/media]

Merry Christmas Gentleman, consider the work in the link below an early present from me.

http://www.cashenblades.com/dryweld.html

Forgive the link to a separate page for this, but it is image heavy and the images would not be very good if reduced so I put together a private page on my web site to bring this information to this thread without a huge use of ABS bandwidth. Also please forgive the slightly fuzzy images, this is an issue I have not been able to resolve in my metallography since I switched to a much higher resolution DSLR.

I have done my share of dry welding in the past due to my work with bloomery material, but this thread caught my interest with the work being done to test it out with wider applications with modern alloys. 15n20 and 10XX is one thing but I decided to push this concept to the limits by using my beloved, yet very ornery, mix of O-1 and L6. The combination of chromium and nickel in these tool steels has always presented a bit more of challenge, not only for the oxides but for the difficulties in the depth of hardening with these alloys when dealing with welding temperatures. On the linked page you will find my metallographic analysis of two billets, one done with borax flux and the other done flux free.

Some things that I would like to add from my experience with fluxless welding is that while I am very pleased with the resulting steel, I did have to alter my usual methods slightly to make things work well. I find what Mike mentioned about going back to his hammer from the press for flux welding corresponds very interestingly to what I found in going in the opposite direction. I do not own a press, but found that when I used my hammer more like a press the dry welding worked better. What I mean by this is that I have very large and flat dies in my hammer and when I do a typical flux weld I start at one end and take the billet in bites to squeeze the flux from one end out to the other. This did not work so well with the dry weld, and when I switched to squashing the entire billet evenly lengthwise in my dies it responded much better. It also responded much better to slow pressing blows rather than fast rapping hits. This all makes sense when you realize that in a dry weld a constant steady pressure bringing all the surfaces into contact at once to exclude the negative effects of oxygen is very important. But with a fluxed weld you have the shielding to take it in steps so long as care is taken not to trap any of the shielding material.

My experience and observations on this process leaves me very impressed with the results of the dry welding approach. It is exciting to think of how streamlined our methods can become when not encumbered by the addition of flux; more efficient forges, cleaner forgings (exterior scale, I mean), less spatter and burn etc… The bar of steel the method so effectively produced appears, at this point, to easily be the equal of any produced with borax. But for me what it all does the most is screams for the answer to the question- if flux is totally unnecessary why has it been a core tenet of pattern welding all these years?

First off, I don’t believe it has forever, and I think one place to look for answers is the beginning the 19th century when intentional alloying changed forge welding along with everything else. After working with bloomery material I see no reason why ancient smiths would have needed flux, the material is so basic and incorporates enough silicates that even if it needed a flux it has its own built in. The other factor is the fuels used and a forge design capable of a deep carburizing layer, a deep bed of charcoal would be ideal, a shallow bed of coal with direct air blast would be miserable, and the gas forge simply negates all of these issues.

Next we need to look at where 19th and 20th century bladesmiths turned to for answers when working out an unknown technique- blacksmiths. Look at the variety of welds that blacksmiths must perform, many, such as the dropped tong weld, involves a lot of exposure of the weld surface to the air before the weld can be sealed; it would just make sense for blacksmiths to adopt a fluxing method, especially after alloying and its more complex oxides were introduced. But now look at the damascus weld in comparison, there couldn’t be a simpler approach than a pre-tacked stack of cleanly prepared steel all kept in the oxygen free atmosphere of the gas forge and quickly sealed in one or two blows. My guess is that in modern times we got our welding methods from blacksmiths and never really questioned if it was all necessary for the simple welds we do.

In conclusion the total control over cleanliness and atmosphere from the gas forge cannot be ignored, but the pure compressive squeeze of the hydraulic press is huge in strongly setting welds in one pop and my microscope is telling me the weld surface preparation is a huge factor as well. I think there are so many things at play here that if we focus solely on the presence or absence of the flux we risk yet another batch of those bladesmithing myths resulting from assumptions based on confused causes and effects. Another error that I am not prepared to make yet is in proclaiming any method inferior or superior to the other. I have seen advantages and shortcomings to both and shouting eureka too soon before all facets have been examined is a good way to eat crow as soon as the next discovery is made, so for now I am just offering what I have seen, but I am very eager to make some more billets with no borax!

Many thanks Kevin for all your work and insight.

John Emmerling

http://www.gearhartironwerks.com

Kevin; quote" Merry Christmas..."

I thought he was going to send out single malt and good cigars!

Merry Christmas to all ya'll too!!!

Mike

|quoted:

Kevin; quote" Merry Christmas..."

I thought he was going to send out single malt and good cigars!

Merry Christmas to all ya'll too!!!

Mike

Sent out, just for my friend Mike! <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Kevin,

THANK YOU for your work and input on this topic! Microscopic analysis of the weld boundaries is exactly what was needed to further the study of this technique.

I agree with you, that the use of fluxing agents began with blacksmiths who were welding together pieces that were heated separately in the forge. The flux providing protection from the forge atmosphere and the proper preparation of the pieces being adequate for ejecting the flux as the weld is made. I think this points out that we might consider getting away from our "one size fits all" mindset and realize that our welding technique should be tailored to the type of interface between the parts to be welded.

Had a chance to try the fluxless weld today. I had three billets to do. I fluxed the first one but got brave and tried the next one without flux. It welded the first try, so I did the third one without flux. Again, it welded on the first try. Two of these are to be "W" pattern's and they held up to the crushing. I did run the forge a little hotter and richer than I normally do.

Dale

Now that I have ground all of the blades from the O-1/L6/O-2 that I dry welded and did the metallography on, I thought I would report back. Everything was very good. Once again am a very hesitant to pronounce anything “better” or “worse”, but this damascus is welded as tightly as any I have ever done, and produces some beautiful blades. Another interesting note that follows with the same characteristics, I did have some very minute black lines as soon as I started cleaning the blades up but these utterly vanished after around 5 to 10 thousandths of grinding, we all know that with borax billets you can chase that line all the way to the other side.

Another thing I like so far is the surface homogeneity, that is my way of describing a subtle difference that some damascus has in grinding, without using misleading terms like “welded more tightly”. We all have seen it when we grind- angle the ground surface in the light and you can see the pattern in the steel where the alloys abraded with a slight difference. I really like it when I simply cannot tell the steel is damascus without having to etch it, I love that level of homogenous quality. This dry welded billet was mostly in that spectrum.

Once again I am looking forward to working some more without flux as in this limited testing I can see no difference in quality, and I actually look forward to being able to establish certain features as better. I know the welding process is a whole lot more pleasant.

http://youtu.be/ZogmHlTmKeM A short Video Nick Rossi took of me during my pattern welded Seax class at NESM, showing the ease and strength of atmospheric welding (bareback welding as JD puts it)

MP

The small amount of experience that I have with welding was without flux. It seemed the key was to hammer with the idea of avoiding making pockets of air. To do this, hammer from one end of the billet to the other, or hammer from the middle of the work toward the outside, in effect pushing any air toward the outside of the steel. Pre-welding the layers together could lock in an air pocket. When forge welding two ends together such as when making a tomahawk handle, scarfing one end makes the weld take better.