Cryonic treatment of rifle barrels.

[ntsqd]

All barrel steel starts as a hot formed bar, not a casting.

How did that molten steel get into that shape from out of the crucible? It was poured into some basic form, be it an incremental process or a continuous process. That makes it a casting. It didn't stay that way for very long as it likely never cooled in that shape, but for a brief time period it was a casting.

Given how secretive, with good reason, most high quality barrel makers are about their exact process I doubt that we'll ever know what each maker does in terms of stress-relieving and heat-treat. I lump cryo in the overall umbrella of "heat-treating" because it is a thermal process. Most such processes that I have read up on employ both low temperature and high temperature in a carefully controlled & timed sequence. I don't think anyone still does only the cold part of the process any more.

 

[tnek13]

I have several custom barrels that are cyro treated as an extra cost suggested by the maker. I also have several custom barrels that are not treated, because that maker told me that if the barrel is properly heat treated and stress relieved that it was not recommended. All the barrels shoot well. Is it worth it, maybe or maybe not? If it shoots good leave it alone, if it needs help it might help.

 

[Buck Fever]

The how it gets out of the crucible and in to a bar is what I would call extrusion but they seem to call it "continuous casting" where it flows out of a nozzle at the bottom of the crucible, is immediately bent 90° and then hot formed to the desired shape.

That's very different from the more common meaning of casting associated with sand casting, die casting and investment casting.

I am disappointed that the steel industry used that term so poorly because the steel never takes on the properties of a casting and as I said, it is hot formed before it solidifies.

So stop telling people barrel steel was cast, if it isn't an outright lie, it's a technicality.

Here is a video of Bohler Udeholm which makes barrel steel:

 

[ntsqd]

Molten metal poured into a form is a casting. It's not a technicality and it is not poor form. And I don't tell people that barrels specifically start out as a casting. I say that all metals start out as a casting. One of my college profs, a PHD in Foundry work, claimed that our school's foundry was the only functioning collegiate foundry west of the Mississippi River. That was over 20 years ago and he sadly just passed away. I miss going to his annual black powder cannon shoots.

 

[J E Custom]

I have several custom barrels that are cyro treated as an extra cost suggested by the maker. I also have several custom barrels that are not treated, because that maker told me that if the barrel is properly heat treated and stress relieved that it was not recommended. All the barrels shoot well. Is it worth it, maybe or maybe not? If it shoots good leave it alone, if it needs help it might help.

The barrel making process dictates the amount of stress relieving required. typically the cut rifled barrels are stress relieved one time from the mill. the buttoned rifled barrels must be stress relieved Twice because of the stresses added by the buttoned process.

I can see the advantage of a cryo treated barrel with cut rifling because it is another form of stress relieving. As stated it is also an extra charge that doesn't add anything to the longevity of a barrel because of the temperature in normal use.

some manufactures will state that it is better because of the money they make by adding extra cost items and you can bet they don't give it to you for their cost. In my opinion it is like fluting, If you want it, pay for it and be happy.

J E CUSTOM

 

[L.Sherm]

I am much more interested in how salt bath nitriding can be used as a last step in a barrel's heat treat to temper the steel, increase corrosion (and erosion) resistance and hopefully do it without screwing up the accuracy. Some companies seem to be able to do it but it's hard to tell which companies have the right process for barrel steels.

I have definitely seen it screw up SS barrels, not chrome moly though.
That being said it was done by one company dont know if it was there process or what.

 

[Sirrated]

As a mechanical engineer i certainly understand the heat treatment philosophy, we see the advantages to that process every day, and it works,,, so when I heard of the Cryogenic treatment, I became very interested as to why we don't discuss it more. Admittedly one would really require the full history of the metal being treated to get the full advantage of any future processes that were being considered, . In today's world we have access to a lot more information of this nature, and that coupled with the experience of many of our members here on LRH is invaluable.
My thanks to all who have contributed to this thread,
I wish you all good health,
"Sir"

 

[25WSM]

My father in law owns one of the biggest steel bar companies in oh. Casting of the bars is technically correct but a loose term of the word casting. The round bars are made round before the casting cools down. So basically they are cast for a few moments before getting formed into round stock. So yeah nothing like a sand casting method where the metal sits till cool. I think the term casting is a bad choice of words but it is what they call it. I would call it partial temporary forming. But what do I know. I just use it when it all done.
Shep

 

[seawolfxix]

Here is a video of Bohler Udeholm which makes barrel steel:

This video shows ingot casting at 2:26. They are not using a continuous caster.

Ingots can be cooled and reheated prior to roll forming.

 

[sw282]

Weatherby's MarkV Super Varmint Master used Kreiger barrels that had been cryoed twice... lf you ever have a chance to acquire one of these MV SVMs they are amazing... Bunch of PD guys l shoot with from TX have several of these guns... All in 22-250, one has 5000+rds thru it... Still accurate as ever.. Couple guys have Kimber that didn't get to #5000, or even 3000. lf l change the barrel on my 700VLS 22-250 it will be a Kreiger... Sadly Weatherby ceased SVM sales... Problem was price...So goes the rumor

 

[Dosh]

In 2010 I won a Vanguard rifle so I thought I'd have the thing cryogenically treated. Removed the bolt and trigger and took it to Cryogenics International in Scottsdale, Az. Four days later I picked it up and put on a Timney and in a bedded B&C stock. Wish I'd shot it first before treatment since it is sub 1/2 MOA out to 500 now. Very easy to clean as well. From all the info on this treatment I've seen the worst result was it can't hurt a barrel. Today, Cryogenics International charges $65-$70 to treat a barrel if there is no disassembly needed. Shillen does not believe in this treatment and will void their warranty if you treat their barrel. I have two rifles with Kreiger barrels and getting another, they shoot very accurately. Bottom line is maybe it works and maybe it just helps!

 

[Sirrated]

Ahhh, Dosh, this is what i've been waiting to hear, My No.1 shooter is a Weatherby and i've been wondering if this process would be worth it. Thank-you.

 

[Dosh]

Ahhh, Dosh, this is what i've been waiting to hear, My No.1 shooter is a Weatherby and i've been wondering if this process would be worth it. Thank-you.

Still don't know if it's worth the bother, all I know is it won't hurt a barrel.

 

[redleg1013]

Well, not to take another kick at a dead horse, but hey...
Cryotreating any steel is going to do a couple of main things: 1) it will "finish" converting austenite to martensite, meaning even after heat treating there isn't a 100 percent conversion, in some steels it's down in to the 80's. The cryo process will get you closer to that 100 percent mark, how much closer depends on the steel and the process. 2) you'll get more carbide precipitates to start showing up —meaning that the wear resistance goes up, and yes, it'll be easier to clean. 3)it helps to refine the grain structure of the steel even further, meaning that yes, it does do some more stress relief (which means that the steel CAN move or distort , but from my experience, it's usually not enough to concern yourself with — it gets finished out) but this again leads to the steel being tougher.

Why doesn't this get done to all steels? Cost and time (which is again cost). There are some steels that have to have it done to make the engineers happy, like every time we've had a job with CPM steels it has to get sent out for cryo. Most of our common tool steels are good to go with a soak and quench.

Speaking of soaking and quenching, I saw someone (please forgive me that I can't remember who said it) mention salt bath nitriding, or nitrocarburizing; just be careful with that temps get between 900 and 1k which may affect the temper of the steel, depending on where they were running the drawback oven. If the re-heat is higher than the initial drawback/temper it will draw that hardness back more. I've never bothered to remember the whole time of the process as we'd send it out anyway, but going back to tempering, some steels only take a couple of minutes as a function of their dimensions, like cooking a turkey at so many minutes per pound.

I hope that this helps clear a couple of things up. No, cryo isn't snake oil, but it isn't a cure-all. I also hope that I didn't come across too high-brow, and if anyone happens to not be a machinist and has a question for better understanding, I'm happy to try to break it down.

(Edited for spelling/grammar)