I am not proficient at all about it but simple search in Google give me this:
How is a gun barrel heat treated?
link
http://ingunowners.com/forums/general-firearms-discussion/113039-how-gun-barrel-heat-treated.html
couple citation:
I've read a lot of guides on how to make your own barrels, but nothing about the proper heat treat/tempering for them. Anyone know something more than nothing about this?
I work for a company that heat treats steel bar, and some of our customers are firearm manufacturers. We get the steel in lengths of 20+ feet and ship them out roughly 8-12" shorter. It's easier to ensure a uniform hardness when the steel is processed in bar stock. The stock is then cut to length and machined into a barrel.
As the button is pulled down the bore and impresses the grooves and lands, metal is displaced. This causes stress in the metal, which can lead to inaccuracy, such as bullets walking off the target as the barrel heats.
Heat treating relieves that stress. Lilja worked as an industrial engineer for the John Deere Company in Iowa before he started in the barrel business in 1985. Part of his time at Deere was spent in the heat treating department. Lilja used to heat treat his barrels himself in a small oven in his shop. His increased production over the years, though, has made it easier to send out the barrels to Spokane, Washington, for heat treating.
Barrels are heat treated to relieve stress from the rifling and threading and other manufacturing processes. Not hardened like receivers on bolt guns.
Hardened steel can be cut with a hacksaw. Just because steel is hardened doesn't mean it's indestructible. Carbide and tool steel are harder than barrels, and explains why you can cut them.
I operated a heat treat furnace for about 5 years, that was 20 years ago.
In general we heated forgings in a 1600 degree furnace that moved on a belt toward the quench for 50 minutes.
After the quench the forgings continued on a belt and were reheated in the draw furnace for about 50 minutes at a temp anywhere from 1100-1400 degrees. The whole process took about 2.5 hours.
Using a Brinell Hardness tester, forgings were very hard after the quench and much softer after the draw. The draw readings were the most important.
I have my precision rifles cryonized "spelled wrong" put in a chamber to -300f it make the gun shoot straighter and improves barrel life.
Steel barrels (not stainless steel) are heat treated and stress revealed after machining and rifling. A mill spec M16/M4 5.56 barrel is hardened to around 30 Rockwell C scale (i think the exact specs are 28 to 33 Rockwell). So technically they are "hardened" but not to the extent that most people think of hardened steel. 30 Rockwell is saw-able and file-able but much stronger than regular steel (which can vary from 3 to 12 Rockwell depending on type). The mil spec barrels are made from chromoly steel usually the 41xx series of alloy steels.
For a comparison, most steel disc targets are hardened to around 52 Rockwell, which is still sorta file-able but is very hard, If it was taken to 60 Rockwell you would pretty much roach the file.
Assuming the barrel you are using is made of the 41xx series of alloys then heating it to anything above 500 degrees could have adverse effects.
Here is a PDF that compares Brinell to Rockwell.
www.universitymachineservices.com/rockwell.pdf
and so on
I am not sure that I understand a half what they talking about, but button point is:
yes barrel's are heat treated. they put to Rockwell hardness around 30, which I assume done to preserve plasticity - returning to initial form when bullet is out and barrel is colling down.
if I understand correctly they heat treat relatively big peace for uniformity and then drill and grind several barrel's from it.
I do not think it to hard with steel as soft as 30 compare 60-65
my husband was showing me a utube movie about bullet going through the barrel in slow motion from Remington 700 rifle
the barrel bend like crazy. it really amazing. that why the newest Remington 700 has a barrel of triangle shape in perpendicular cut instead of classic round one - they claim that this increase stability of the barrel.
so basically all the same depending of task:
both barrels and knives are heat treated
heat treatment depend of task:
for barrels you need strength and toughness - do not crack and terrain the from
for knives edge retention, stain resisting and so on
if you pay attention they mentioned that some other part of rifle or gun also heat treated but to different degree hardness depending of task
) is that barrels are (probably) made from automatic / continuous hot forged stock that has been HT'd during the manufacturing process and then milled / machined to take their final form. Knives are open-die drop forged (drop as in dropping a hammer on the steel atop an anvil), and are molecularly changed a few times during the process; again to affect malleability during the forging process, then again during the HT.
