Effect of blueing on color case hardening

[oldhenry]

I'm prepping a Rem. 521T for blueing. The bolt handle & rear bolt shroud are case hardened. I seem to recall that when the case colors are removed by polishing the conventional re-blue process produces an even purple color over the part. If that is what happens, I may just have to live with it.

Back in the '70s I made a muzzle loader from a kit. To add a little personal touch I heat blued all of the screw heads. I found that I could produce different colors with varying temperatures & the colors looked like case colors.

My question: would the larger bolt parts (bolt handle & rear shroud) if heat blued survive the opening & closing of the bolt any better or worse than conventional blue?

Any input will be appreciated.

Henry

[john.k]

The loss of hardening in the wear parts would be far more serious than any effect on the cosmetics....if you want to blue bolt parts use either hot solution,or slow rust process

[Bent Ramrod]

Heat bluing as you describe is a very thin and fragile coating of iron oxide. A heat-blued screw that is set in place and not messed with might not be affected much, but a large part blued that way would wear bright from handling very quickly.

There are some “heat blues” that are more wear-resistant, like that from heating carbon steel to cherry-red and quenching in oil, or the Carbona process that used to be done on revolvers, but both of these processes were either a part of the heat treatment, or the parts were heat treated afterwards.

Heating a large, stressed part to a blue color in air would anneal the surface (if it is casehardened) and make it prone to wear and battering in use.

[oldhenry]

john.k & Bent Ramrod,

Thanks for sharing your expertise with me.

Henry

[Geezer in NH]

For hardening hot caustic blue does not hurt casehardening, for the case colors bye bye, most every thing hurts the colors as they are micron thick. That is why the get covered in clear lacquer.