hardening silicon bronze

[HSC ///]

I used silicon bronze alot, guards, ferrules, bolsters etc.
Anyone know if silicon bronze can be hardened? It comes half hard.
I contacted Atlas Metal who referred me to National Bronze and they indicated they have not see SB hardened.
@mete I saw your response on an old thread, any insight?

 

[running bird]

From what I understand you have to work harden silicon bronze like you would other similar alloys. And silicon bronze can be more easily hot forged than others.

I would assume when the manufacturer says their bronze comes half hard they mean it was formed to shape and not fully annealed.

I don’t work with silicon bronze but I have been reading into it and aluminum bronze for a bit, so hopefully someone with more practical experience working with it will come by.

 

[HSC ///]

specifically my interest is to use SB for a slipjoint folder frame.
so I'll be machining it
so I want it as hard as possible,

 

[john april]

i remember reading somewhere non-ferrous metals are hardened the opposite of ferrous metals. heat red hot and let it cool slowly to harden. heat red hot and quench in water to anneal/soften. i think the info was from a japanese habaki tutorial. maybe someone with a hardness tester can check the accuracy of the info.

 

[Stacy E. Apelt - Bladesmith]

Sort of what John said .... sort of.

Non-ferrous metals are hardened by heating to a specific frange, usually around 700-900F, and holding for a length of time. Then it is slow cooled. This will harden it a bit, but it isn't HARD like steel gets.
Annealing is done by heating to near dull red (around 1000-1200F) and immediately cooling. Most folks let the color drop to black and then immerse in water or pickel.
The others way of hardening is work hardening. This is done by hammering or rolling the stock. Too much and it cracks so it requires some skill. Work hardened metals are normally more brittle.

Non-ferrous metals are usually offered half-hard and annealed. Half-hard is about as hard as these metals get , so it is technically full hard. After machining, sanding, polishing, etc. it may be a tad harder.

Another way of hardening a finished or semi-finished bronze object it to tumble it in a shot tumbler for an hour or two. That should harden the surface to the max.

I don't know the numbers out of my head, but I tend to think a frame lock will have wear issues in silicon bronze .... hardened or not.

 

[HSC ///]

Non-ferrous metals are usually offered half-hard and annealed. Half-hard is about as hard as these metals get , so it is technically full hard. After machining, sanding, polishing, etc. it may be a tad harder.

I don't know the numbers out of my head, but I tend to think a frame lock will have wear issues in silicon bronze .... hardened or not.

This will be for a slipjoint integral bolster/frame to secure the spring pins and pivot pin, I think it will work fine as it is - half hard.

 

[Stacy E. Apelt - Bladesmith]

My bad, somehow I read "frame lock" into your post. For integral bolster/liners, use it half hard.

 

[me2]

Have you been able to find full hard Si Bronze? I was digging into hardenable bronze alloys a while back because I thought about trying a bronze knife. It was a bit expensive for just curiosity and novelty. I'll have to recheck some stuff. The Al Bronzes could be heat treated to respectable strengths, but the times and temperatures were different, with the times being considerably longer. The basic procedure was heat, quench, reheat. Temperatures and times were alloy specific.

More on topic, I'm pretty sure I had some slip joints with brass liners. I would think if brass would work, Si Bronze would be fine.

 

[HSC ///]

Have you been able to find full hard Si Bronze?

More on topic, I'm pretty sure I had some slip joints with brass liners. I would think if brass would work, Si Bronze would be fine.

no I haven't, I didn't think of that...I was trying to use the material I had in stock.

good point on the brass liners, and I've used brass liners myself in some early practice slipjoints.