Swapping handlebars

[daz]

. . . To anneal copper you must cool it slowly. Plunge it in water and you temper it--hardening. . . .

Hi PITAPan. Major Softie has already corrected you that copper doesn't harden when red hot and plunging it into water. So I don't need to address that. But in the steel heat treating world "tempering" has a specific purpose and meaning.

In heat treating steel, only high carbon steel can be heat treated. That is a two operation process (three if you want to include cryo-treating). At elevated temperatures (the often used phrase "cherry red") the carbon in high carbon steel goes into solution with the iron. If you cool the steel fast enough the carbon doesn't have the time it needs to migrate from the iron and collect into carbon nodules. That is, it remains in solution by degrees. (Here's where I get a bit vague.) The carbon atoms, still in solution with the iron atoms, interfere with the iron molecular structure such that elasticity in inhibited. The resultant steel is very hard and very brittle. Too hard and brittle for many applications. The steel acts much like glass and can be fractured with a hard enough blow.

Ken

Nice job Ken. I would only add (because it's interesting) that at the point the carbon steel is cherry red is also the point the steel looses its magnetic properties.

[Deleted User 287]

There are some fun and sometimes useful things you can do with carbon steel.

Did you say "fun"???

Well lads, it's been nice, but I am off for a weeks holiday. ( )

[jagarra]

when I have made a firearm part from steel to harden it I got it cherry red and quenched it in oil, supposedly made it hard but not brittle. Another method described was to lay a small part in a container of oil and set it on fire, don't quite know how well that works, but it was described in the process of forming leaf springs.

[Ken in Oklahoma]

when I have made a firearm part from steel to harden it I got it cherry red and quenched it in oil, supposedly made it hard but not brittle. Another method described was to lay a small part in a container of oil and set it on fire, don't quite know how well that works, but it was described in the process of forming leaf springs.

I know that some steel formulations are intended for oil quenching. But if you don't know the type of steel and recommended quenching protocol, the results would seem a bit iffy. How do you really know how hard and how flexible the result is?

Personally I would be way more comfortable quenching in water and then going through a separate tempering process aiming for the oxidation color I wanted. Certain parts demand more flexibility and others demand greater hardness. For example a firing pin or a shell extractor I would want to be not so brittle that it might fail in the field. And so I would be willing to give up some hardness (and wear resistance) to get durability and resistance to shock.

You can get some indication of hardness by testing your work with a file. A file is tempered very hard and that's why files are sometimes broken, especially if dropped on a hard surface or used carelessly. But the tradeoff with a file that can break is that it will stay sharp longer. If you try a file on a quenched but untempered piece of high carbon steel, the file won't touch it. The file will skate right across it. If you press harder the file itself can be easily damaged that way. When I use a file to test hardness I use a part of the file that is seldom used, such as toward the very heel of the file. That way when you damage some teeth, it's in a part of the file that you don't use much anyhow.

Ken

[Major Softie]

Yes, some steels are formulated for water quenching, some for oil quenching. Still the best balance of hardness and toughness is then delivered by gently reheating the part to a predetermined lower temperature to "temper" it (reducing brittleness and choosing the exact balance between toughness and hardness). Another very effective technique often used for older gun parts was "case-hardening," which is very useful for smaller parts that have to have a very hard surface but still retain toughness to prevent breakage (such as hammers, for instance). Case-hardened parts are heated and the hot part is plunged into a case-hardening carbon compound.

Case-hardening is a very fast process, demands less expertise than tempering, and leaves an extremely hard surface while retaining a softer interior. This works really well on the small working parts of firearms.

(it's also really pretty)

[Ken in Oklahoma]

. . . (it's also really pretty)

It is that! And it looks so, well, right on a gun.

I've often wondered why we don't see more of it, especially on antique replicas, but also "modern" guns with a nod to the past. The best guess I can come up with is that, simple as it is, case hardening is relatively labor intensive in a modern factory environment.

Ken

[melville]

To anneal copper you must cool it slowly. Plunge it in water and you temper it--hardening.

Sorry. Completely wrong. This is true for steel, but not for copper. Copper can be heated and quenched and it's still annealed. Some sources even say that if you don't quench it fast enough it will not anneal, but I've never experienced that.

Indeed, I just did this for some VW T4 exhaust gaskets. They are shipped hard--when dropped, they 'ring.' With just a modest propane annealing, including a dunk in cold water, they then 'tunk' when dropped.

[Major Softie]

. . . (it's also really pretty)

It is that! And it looks so, well, right on a gun.

I've often wondered why we don't see more of it, especially on antique replicas, but also "modern" guns with a nod to the past. The best guess I can come up with is that, simple as it is, case hardening is relatively labor intensive in a modern factory environment.

Ken

I think part of it is that we have so many tool steels now that were unavailable to them then. Even so, some modern revolvers still case-harden their hammers. Lots of replica manufacturers, like Uberti, still use a lot of it: hammers, triggers, and even frames.

[PITAPan]

when I have made a firearm part from steel to harden it I got it cherry red and quenched it in oil, supposedly made it hard but not brittle. Another method described was to lay a small part in a container of oil and set it on fire, don't quite know how well that works, but it was described in the process of forming leaf springs.

I know that some steel formulations are intended for oil quenching. But if you don't know the type of steel and recommended quenching protocol, the results would seem a bit iffy. How do you really know how hard and how flexible the result is?

Personally I would be way more comfortable quenching in water and then going through a separate tempering process aiming for the oxidation color I wanted. Certain parts demand more flexibility and others demand greater hardness. For example a firing pin or a shell extractor I would want to be not so brittle that it might fail in the field. And so I would be willing to give up some hardness (and wear resistance) to get durability and resistance to shock.

You can get some indication of hardness by testing your work with a file. A file is tempered very hard and that's why files are sometimes broken, especially if dropped on a hard surface or used carelessly. But the tradeoff with a file that can break is that it will stay sharp longer. If you try a file on a quenched but untempered piece of high carbon steel, the file won't touch it. The file will skate right across it. If you press harder the file itself can be easily damaged that way. When I use a file to test hardness I use a part of the file that is seldom used, such as toward the very heel of the file. That way when you damage some teeth, it's in a part of the file that you don't use much anyhow.

Ken

When you buy the steel, you know what it is. Sez on the sales lit. Found material, anybodies guess. I've salvaged coil springs and got some spring back in my messed up dipstick, but I was completely guessing. I gave the dipstick two rounds @ a scant 1150F w/ a water quench. Did the spring at bright red with a single oil quench. You have to use the right oil. Reworkinh hard steel, like hacksaw and bandsaw blades you can usually guess. An oil quench would be my first try. You can always re-do it. I've micro-annealed wide clock springs (for drilling) but I didn't try hardening them again, I just didn't soften the parts I needed springy. I'm missing a spring for a firearm and I'm tempted to try making one, but it's awful small.....

You can do bluing with oil at pretty low temp, air quench. Works nice on mild steel, wrought iron, etc.




heat treat shops know the full protocols; temp, soak, quench, repeat, etc. They can also do carburizing and case work.

[timkil]

Wow, All this for a set of handlebars. I had no idea. Happen often?.........Thanks to all contributors, I'll be using garden fresh washers.