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