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James Simonds

Bronze Pattern welding.

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Hiya bladesmiths.

 

So, i am equipping my new tiny backyard workshop with a paragon tempering oven, i dont have room/capacity/safe environment for a gas forge. its a very VERY closepacked residential area. one of the plus sides to this is that i really am enjoying experimenting with bronze for blades as well as fittings. A tempering over is perfect for forging bronze.

 

One of my long term quests is to make bronze pattern welded blades that are hardenable, or san mai style with a hardenable core and softer outsides if 2 hardenable types dont exist with enough constrast perhaps.

 

I know that some grades of aluminium bronze are quench hardenable, and that most are work hardenable to some extent. so, i think it should be possible to make a pretty decent blade with bronze pattern welded material.

 

There is almost 0 info out that on the wide web about bronze forging blades in general, and pattern welding it specifically. i've looked at various mokume gane tutorials, and i guess they have relevance, but has anyone here tried forging different bronze grades together? im considering various methods.

 

1. Heat them while they are loosely held together and hit them with hammer.

2. heat them while the are compressed together with a screw plate or something, then hit them with a hammer

3. brazing and then hitting with a hammer. not sure that works, because forging temperature is a bit high to allow a brazed joint to be forged?

4. screwing them tightly together and simply holding them at forging temp for aaaaaggggggggggeeeeeeesssss. but, pattern welding that way would be a slow process

 

So, does anyone have any expereince or tips? my paragon will arrive in a couple of weeks and i can start experimenting. i have two types of phosphor bronze, PB2 and PB102. i have copper, regular brass, Aluminium bronze (CW307?) and some SAE660. i also have some 'ancient' style bronze casting that i can play with. now, i have been told the ancient style bronze wont forge, too much tin content, and that the same is probably true of the 660 although higher levels of lead might make it ok. the PB102 forges absolutely beautifully, its gorgeous to work hot and i've done some stuff with it already, and the aluminium bronze forges well too, although not tried this grade.

 

Any other tips, advice, info etc. would be appreciated.

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Mokume gane is pretty much the only way to do this that I know of.  I could easily be wrong, but most nonferrous metals do not behave like steel.  I mean, you can forge-weld pure gold or pure silver at room temperature, but all the others tend to have an oxide layer that only gets worse at heat.  

 

I would be sure to have a sacrificial floor in the Paragon.  You will melt some alloys in there, and it'll be difficult to remove.  A bit of kiln shelf, or even better a tray made from castable refractory so it will catch the runs before they get into the side bricks.  

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James, do you Facebook? There is a FB group called Experimental Historical Bronze Casting. Although they focus on casting bronze, they might be able to guide you to some info.

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2 hours ago, Joshua States said:

James, do you Facebook? There is a FB group called Experimental Historical Bronze Casting. Although they focus on casting bronze, they might be able to guide you to some info.

It's not a topic for that group, as it focusses on recreating techniques from the past only. 

 

The important thing is how do the alloys you want to fuse together behave at the right temperature. Are they forgeable at that heat? Traditional tin bronze isn''t, it will just crumble . The only way to fuse those is to have alloys with enough difference in melting point, and have one melt while the other stays solid. A trick to make that easier is to melt the bronze with the low melting point first in a crucible, take the crucible out of the furnace, and stick the other alloy into the crucible. That way the colder metal will cool the liquid bronze, so it will all solidify into a solid lump. And then you have to cut that to size, and cold work/anneal if you want to work it further.

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4 hours ago, Jeroen Zuiderwijk said:

It's not a topic for that group, as it focusses on recreating techniques from the past only. 

 

The important thing is how do the alloys you want to fuse together behave at the right temperature. Are they forgeable at that heat? Traditional tin bronze isn''t, it will just crumble . The only way to fuse those is to have alloys with enough difference in melting point, and have one melt while the other stays solid. A trick to make that easier is to melt the bronze with the low melting point first in a crucible, take the crucible out of the furnace, and stick the other alloy into the crucible. That way the colder metal will cool the liquid bronze, so it will all solidify into a solid lump. And then you have to cut that to size, and cold work/anneal if you want to work it further.

 

Well, i know two of the bronze grades forge very well. the phosphor bronze and the aluminium bronze. Yes, it is true that not all grades do, and i think the SAE660 lead/tin bronze will not forge.

 

Very interesting idea to see if i can semi-cast a combined metal. i could do that with a crucible or more likely a tray type arrangement in the heat treating oven. i had not considered that approach. it would have the advantage of being totally gap filling aswell. if i did that with the phosphor and aluminium bronzes, then i could forge the resulting billet and have some very cool possibilities patternwise with appropriate forging and grinding.

 

Thanks

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