Does brass "work harden"?

[SteveMP]

Not sure if thats the right term. But anyhoo, I was working on some tools using some folded brass saw backs, and noticed I could usually cut them no problem, and sand and file etc. But a couple of times when filing, all of a sudden the file would kind of "skate" across the brass, and make a higher pitched sound. Almost like if you try to file a plane iron or something hardened. At first I thought maybe the file was clogged, but tried cleaning with a card file and using other parts of the file. Ended up switching to wet dry sandpaper and that worked. But got me curious if I was doing something wrong, and if it did harden, should I do something to fix it? Or is a a hardened saw back not a big deal.

 

[NickM]

I don’t know if it’s your problem here, but brass does work harden. It’s possible to anneal (a heating process) it to soften it again.

(I only know this because I do some target rifle shooting. The cartridge cases are brass and have to be re-sized after each firing. Without annealing, they will work harden and eventually crack.)

 

[Woodbloke]

Not sure if thats the right term. But anyhoo, I was working on some tools using some folded brass saw backs, and noticed I could usually cut them no problem, and sand and file etc. But a couple of times when filing, all of a sudden the file would kind of "skate" across the brass, and make a higher pitched sound.

That means that your file is also slightly blunt, as well as the brass work hardening. You can easily get away with used files (to a point) on mild steel, but ideally brass demands a brand new one - Rob

 

[CHJ]

To soften work hardened Brass to reduce fracture risk whilst bending etc.

Ensure brass is clean (no oil dirt etc.)
Heat to just reaching Dull Red (400C?)
Allow to cool in air (Do not Quench)