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Thread: Strength of stainless steel Guns vs carbon steel guns

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    Default Strength of stainless steel Guns vs carbon steel guns

    This subject is prompted by my purchase of a blued Ruger .44 mag at the gun show this weekend. I noted that this gun is avalaible in both blued and stainless models.

    While the positive attributes of stainless steel guns are well known the negative side of stainless steel is less apparent: at room temperatures stainless steel alloys are not as strong as carbon steel alloys. Although the ranges of the tensile stregths generally overlap the best carbon steel alloys are inherently stronger than the best stainless alloys. This factor is evident in the design of industrial high pressure piping systems and valves for example.

    While in practice no one should be loading a handgun to those pressure levels anyway a handgun constructed of a high strenth carbon steel alloy should be able to handle hotter loads than an identical gun fabricated of stainless. The most critical part would probably be the cylinder on a revolver due to the relatively thin cylinder walls.

    As I recall some of the first .454s were made with high strenth carbon steel alloy five shot cylinders but that was about 50 yrs ago before stainless steel guns were around. I have also read about some of the issues Ruger had in selecting an alloy for the cylinders of the orginal .454 Super Blackhawks.

    Anyone have any thoughts, knowledge, or real life expereince with this subject?

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    This is something that I read a few years ago.
    http://forum.m1911.org/showthread.ph...highlight=asme

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    I doubt the perceived "strength" of either a blued or SS weapon matters to the consumer. Booth type of steels are "proofed" by either the manufactor or an independent lab to prove they are strong enough for there intended use.
    Peyton, Colorado

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    Default Stainless -vs- Blued Steel

    http://www.benchrest.com/forums/showthread.php?t=17626

    I saw this a while back and thought it was interesting. It shows a Sako stainless barrel failure, which Sako and Tika issued a recall for. I agree with Snowwolf, stainless or blued, both or tested for their intended use. But I do think the error factor with stainless is less forgiving. I now have more stainless firearms than blued, I guess I'm hoping no imperfections show up unannounced. Lastly, I'm sure more gun failures are due to operator error than manufacturing error.

    Woody

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    Well let's see here how shall I say this. I think you are wrong about the strength of stainless vs carbon steel. Using the revolver as a reference, there is no doubt that the stainless steel used by Ruger and Freedom arms is significantly stronger than the "standard" chrome/moly steel used in blued guns. The 454 was the test vehicle and catalist for the development of this new age super strong stainless steel. There was not a 454 made in a C/M steel revolver fifty years ago for several reasons. There was no such caliber fifty years ago. Dick Casull needed stronger steel to contain his 65,000 psi cartridge and went to the very expensive but very strong stainless that is used today by FA and Ruger and more recently S&W for there 460 and 500 S&W cartridges. This same steel is modified only slightly to allow it to be blued by reducing the chrome content and it is now the strongest C/M steel available but it was a recent development, spawned by the stainless which was first used in the gun industry in the 1970's. So the stainless steel needed for the 454 Casull cartridge is what brought about the higher strength of todays stainless and C/M steels.

    But rest assured any gun made today and chambered for even an old caliber is much stronger than ever before. Also in keeping with the revolver, these newer steels are much more flame and errosion resistant and we don't have to worry much about extensive shooting of high velocity loads cutting through the top strap of revolvers. Stainless steels are even more resistant to the flame cutting from the cylinder gap flash.

    Even in the 1960's gun companies were going to stainless steel for the high velocity magnum calibers because of it's strength and errosion resistance. This evidenced by the 264 Win and 7mm Rem original debut was with stainless steel. Stainless was more expensive back then and that was it's main draw back.

    This new space age stainless steel is called 17-4PH which is 17% chromium, 4% nickel and almost 1% Molybdenum. It is very strong but not so corrosion and rust resistant as some but much stronger than any of the 400 series steels.
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    Well said Murphy, I think the gun companies have really researched this carbon and stainless thing out, just like all the trouble Ruger went to. I think revolvers, pistols and riles are much better today because of the fine grade of steel being used today. I know one thing for sure that throats last a lot longer in rifles today than they did back in the late 60's and early 70' when I started shooting magnums and firing a lot of rounds through them.
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    [QUOTE=Murphy;199617]
    Even in the 1960's gun companies were going to stainless steel for the high velocity magnum calibers because of it's strength and errosion resistance. This evidenced by the 264 Win and 7mm Rem original debut was with stainless steel. Stainless was more expensive back then and that was it's main draw back.
    QUOTE]

    Murphy:
    I have an early model 700 Rem. in 7mm Rem. Mag. and have wondered if it had a SS barrel.

    Is there any way to tell if it it has one of the Stainless Steel barrels, that you know of?

    My gunsmith seemed to think that it would be marked, if it was. I've found no marking that would indicate to me one way or the other.
    Thanks
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    Default More information on SS vs CS Alloys

    Murphy- I appreciate your concerns about offending me but I'm pretty thick skinned One the other hand I do my research and don't get proven wrong too often. Allow me now to make a few corrections on what you stated:

    While there are some stainless steel alloys that are stronger than some carbon steel alloys the strongest steel are not stainless alloys. The high nickel content of stainless steels and other factors limit their untimate strength. The CarTech website www.cartech.com has a lot of information showing the strength an properties of alloys. While stainless alloys exceed in corrision resistance carbon steel alloys are inherently stronger materials.

    The stainless steel used in the Ruger revolvers is actually CarTech Custom 465 - it is not not 17-4 - according to CarTech who supplies Ruger the steel. This 465 alloy was designed for the Aerospace industy - not the firearms industry. Bill picked it up some time later for the Super Redhawk.

    According to my Catridges of the World the .454 was developed in 1957 - around 50 years ago by my calendar. I remember reading about in the late 50s or early 60s when they were building guns on Blackhawk frames with 5 shot cylinders.


    Quote Originally Posted by Murphy View Post
    Well let's see here how shall I say this. I think you are wrong about the strength of stainless vs carbon steel.

    The 454 was the test vehicle and catalist for the development of this new age super strong stainless steel.

    There was not a 454 made in a C/M steel revolver fifty years ago for several reasons. There was no such caliber fifty years ago.

    So the stainless steel needed for the 454 Casull cartridge is what brought about the higher strength of todays stainless and C/M steels.

    Even in the 1960's gun companies were going to stainless steel for the high velocity magnum calibers because of it's strength and errosion resistance.

    This new space age stainless steel is called 17-4PH which is 17% chromium, 4% nickel and almost 1% Molybdenum. It is very strong but not so corrosion and rust resistant as some but much stronger than any of the 400 series steels.

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    I seem to recall that Darcy Echols would not use stainless in some of his rifles if he thought a guy might use it for polar bears. I was always under them impression the stainless was not as strong as cro/mo, all things being equal. However, it is more resistant to flame-cutting from the powder burn and machines more easily than cro/mo, which is why 99% of competitive shooters use it.

    If you're not familiar with Darcy Echols, he uses M70 actions that he works over, then puts them in stocks of his designs and I think he only chambers for belted magnums. Lots of guys heading for Africa think he is the best guy to build a DG gun. Used car to new car prices.

    For most of us, I suspect that there is quite a safety margin built into our rifles, regardless of steel.

    Doug

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    Default SS in the Arctic i.e. polar bear hunting

    I'm not familiar with Darcy but I do recall reading somethiing where the thought is that SS contracts more at colder temperatures than CS and the bore of the rifle becomes too small. Otherwise I can not imagine why he would not want to use SS for hunting polar bears. In addition to its corrosion resistance and flame errosion resistant SS in general is actually better for extreme low temperatures than CS. SS in general has a lower ductile temperature than carbon steel and will continue to be flexiable below the point where carbon steel becomes brittle.

    I'm not sure about barrel steels but in general SS is a bit tougher to machine that CS. SS tends to tear and gall where carbon steel cuts with a smoother action.

    Incidently galling or sticking of two surfaces is one of the big obstacles that had to be overcome in developing SS firearms. On semiauto handguns I understand that the frame and slide are actually made of different allows to avoid galling.


    Quote Originally Posted by dougk View Post
    I seem to recall that Darcy Echols would not use stainless in some of his rifles if he thought a guy might use it for polar bears. I was always under them impression the stainless was not as strong as cro/mo, all things being equal. However, it is more resistant to flame-cutting from the powder burn and machines more easily than cro/mo, which is why 99% of competitive shooters use it.

    If you're not familiar with Darcy Echols, he uses M70 actions that he works over, then puts them in stocks of his designs and I think he only chambers for belted magnums. Lots of guys heading for Africa think he is the best guy to build a DG gun. Used car to new car prices.

    For most of us, I suspect that there is quite a safety margin built into our rifles, regardless of steel.

    Doug

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    tvfinak, this has been some very, very interesting reading. I am just glad that in our day the steel is of a very good quality which represents a good margin of safety for us shooters and hunters and especially handloaders (who load with in the safe margins of loading manuals). Thanks for the info and insights on CS versus SS, I for one found it very interesting.
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    Yes, this is a very interesting and informative discussion. I am positive that the United States Department of Defense has conducted extensive testing on this topic through the US Naval Research Laboratory and the US Army Natick Labs and the Cold Region Test Center. I personally have negative knowledge reference these results. If someone has access to this research data it sure would be beneficial to this discussion if they could illuminate us American taxpayers with the unclassified truth.


    "AND YE SHALL KNOW THE TRUTH AND THE TRUTH SHALL MAKE YOU FREE."

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    Quote Originally Posted by tvfinak View Post
    Murphy- I appreciate your concerns about offending me but I'm pretty thick skinned One the other hand I do my research and don't get proven wrong too often. Allow me now to make a few corrections on what you stated:

    While there are some stainless steel alloys that are stronger than some carbon steel alloys the strongest steel are not stainless alloys. The high nickel content of stainless steels and other factors limit their untimate strength. The CarTech website www.cartech.com has a lot of information showing the strength an properties of alloys. While stainless alloys exceed in corrision resistance carbon steel alloys are inherently stronger materials.

    The stainless steel used in the Ruger revolvers is actually CarTech Custom 465 - it is not not 17-4 - according to CarTech who supplies Ruger the steel. This 465 alloy was designed for the Aerospace industy - not the firearms industry. Bill picked it up some time later for the Super Redhawk.

    According to my Catridges of the World the .454 was developed in 1957 - around 50 years ago by my calendar. I remember reading about in the late 50s or early 60s when they were building guns on Blackhawk frames with 5 shot cylinders.

    I guess your right it has been fifty years. But remember when Dick Casull started making his own guns their were of stainless. I cannot say for sure which stainless but they are stainless. An employee of Freedom Arms, a few years ago, told me Ruger had recently started making their revolvers from a steel "very similar to the steel FA has been using all along". He also told me there wasn't a C/M alloy that was strong enough. The 465 you mentioned is a Carpenter steel and it is of very recent development, about the last 10 years or so, and it may now be Ruger's steel for some applications, such as revolver cylinders but probably not for barrels or actions I'm pretty sure actions of rifles are made of 17-4. Carpenter Technology may very well supply this steel to Ruger. Ruger investment casts all of its frames, receivers and smaller parts. Carpenter is a supplier of the powder metal technology to many users, and would very likely be the supplier to Ruger. This powdered metal has all the exact right elements at the right % and is melted and forced into the mold under pressure and makes metalurgically near perfect parts. The raw metal has to be clean and free of impurities or things go south.

    Ed Harris who used to work for Ruger has written a lot about the various steels particularly for barrels and the said that now Ruger uses 415 R for its revolver cylinders and it is hardnened to RC 35. (thats pretty hard for stainless usually they are 21-24.) I know their cylinders are very hard.

    Gale McMillan, in some paper that I have about his barrels said, rifle barrels are 416R or 415R and most makers actions are 1704, (meaning 17-04, meaning 17% chromium and 4% nickel) or 17-4PH (Precipitation Hardened).

    I don't think anybody makes stainless barrels from anything other than 415R or 416R today. These steels are strong, but probably not the same tensile strength of the CM 4140 or 4340 used for the same purpose. So I'll say I was wrong if I said barrels are made from anything else. But you don't get any points because I've been wrong before.

    Also I think, because of the way steel must perform that it isn't likely that anybody makes receivers from the 415/416 steels now days. But maybe they do. These steels are know as 18/8 or 1808, or 18-8 in the US meaning 18 % chromium and 8% nickel. I do think the newer 465 might just be the steel to use because it's yield strength can be as high as 250 Kpsi. I don't know if barrels would be better made from it. I think this is the steel that has a % of Titanium in it.

    Stainless is easier to machine than C/M and can be machined to closer tollerances so barrels are general more precise and more accurate. These stainless steels are less temperature tollerant and their elastomeric properties (expansion and contraction) are reduced in extreme cold conditions. This has given cause to worry some barrel makers and shooters when on polar bear hunts. Stainless is easier to damage when cleaning from mechanical stresses ( cleaning jag) but is more tollerant of the various chemicals used as solvents. So Sweets is less likely to damage a s/s barrel but a bad rod or jag might.

    I don't know what the actual yield strength of the C/M steel of today but 4140 was once known as HY-140, meaning 140 Kpsi strength. They made submarine hulls from it for decades. There is a certain toughness of this stuff that makes it difficult to machine and helps it hold it's shape better than the 416 series s/s. It does perform better in temperature extremes than the 416 series stainless.

    When you say carbon steel is stronger, certainly the 1% carbon and higher steels are the strongest and toughest stuff but we can't machine many of these steels. They make great knives when forged to shape and the hold an edge well and almost are indestructable but to make a gun there is extensive machining involved so there will be less carbon and no more than about 1% molybdenum. Without a doubt my 01 steel (1% carbon) Randall knife is stronger than the 416 stainless guard, but there was never a mill put to this tough old steel.

    I might be talking about somethin I know nothing about. I read alot, I learned to read in the 8th grade, but I find very little continuity in information about steels used in barrels or cylinders or receivers. I think stainless is too shiny and I think Blue steel is 'purdy'.

    I apologize for saying you were wrong, obviously you have done your research. I hope some folks have found this interesting or at least entertaining. Thanks for keeping me straight.

    Edit: I did find confirmation this morning that Freedom Arms does now and always has used 17-4 Stainless steel, this was stuck in my memory from somewhere. I've owned several FA guns and did remember the steel being 17-4.

    Also, I did get confirmation that Ruger uses 410 stainless in all handguns and frames of the Super Redhawk, but the cylinder and barrels of the 454 (maybe other calibers as well) are made of the newer, aerospace 465 steel. This steel is of the 15-5 family with some added component to make it more machinable, as 15-5 is too tough to machine except for very slow feed applications. This would make it cost prohibitive for Ruger. This revolver in 454 has a cylinder the same external size as the 44 mag so it is thinner walls than the 44 as it is also six shots, one up on the FA guns. The 454 is spec'ed at 65,000 psi and the industry proof is 140% of spec. That puts very high strength requirement on this six shot revolver. To make this cylinder so thin the steel must be very strong. It is. It is also very elastic, one reason for the great strength. This elastic property is why Ruger has had problems with cases sticking. The cylinder expands, so does the brass, the cylinder then contracts, the brass does not.

    I asked this Ruger engineer, Steve; "Is this as strong as the best chrome/moly?" He replied; "Well, you don't see any 454 made in C/M."

    You are right about this new space age stainless, it is the chosen material for barrels and cylinders of the SRH (at least in the 454 Casull). And you may very well be correct in saying that C/M is stronger than some stainless, but until a C/M 454 revolver rolls off the production line, I'll withhold judgment. Also I'll say that for a rifle, as always, I want mine made of good Chrome/Moly steel.
    Last edited by Murphy; 01-23-2008 at 08:57.
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    [quote=Smitty of the North;199823]
    Quote Originally Posted by Murphy View Post
    Even in the 1960's gun companies were going to stainless steel for the high velocity magnum calibers because of it's strength and errosion resistance. This evidenced by the 264 Win and 7mm Rem original debut was with stainless steel. Stainless was more expensive back then and that was it's main draw back.
    QUOTE]

    Murphy:
    I have an early model 700 Rem. in 7mm Rem. Mag. and have wondered if it had a SS barrel.

    Is there any way to tell if it it has one of the Stainless Steel barrels, that you know of?

    .......
    Smitty of the North
    Smitty,

    John Lacy's book of the M700 Remington history gives details of the markings and dates for the stainless barrels. I don't have my book here with me and can't recall the exact details. If you're M700 fan or for anyone this is a very good book with great pictures of Remingtons and all the little details.
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    Murphy:
    HOKAY, Thanks
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    Default Development of the .454 Ruger

    I finally found the following article on the CarTech Site: Don't know if the links will work or not but interesting reading in any event. Note the date before reading.


    ONE OF THE WORLD'S MOST POWERFUL REVOLVERS GETS LIFT FROM AEROSPACE ALLOYS
    August, 2000
    The new Ruger Super Redhawk .454 Casull is one of the most powerful commercially available revolvers in the world, and a classic study in creative materials management and design.

    This big-bore handgun, developed by fine firearms manufacturer Sturm Ruger & Co., Inc., Southport, CT, was designed from the start to withstand the very high stresses generated by the .454 Casull cartridge. The .454 Casull is one of the most powerful revolver cartridges made.

    Wilderness guides, hunters, fishermen and experienced shooters use the powerful sidearm to hunt dangerous game such as brown and grizzly bear, elk and jungle cats. With this revolver, a skilled marksman can drop a large animal at a distance of up to 200 yards! In addition to big-game hunting, the Super Redhawk .454 Casull is also used for target shooting at metallic animal silhouettes.

    The massive, high strength frame of the rugged, double-action revolver has been key to its reliability and durability. More particularly, the specially designed cylinder and barrel, made from state-of-the art aerospace alloys, have been critical to its outstanding performance.

    The Cylinder
    Ruger's goal was to develop the firearms industry's first and only six-shot revolver in a .454
    Casull caliber. Designers started with the proven, rugged .44 magnum platform, planning to step it up to successfully withstand the higher pressures produced by the .454 Casull cartridge.

    The highest chamber pressure created when firing a .44 mag. revolver is about 42,000 psi. That compares with approximately 62,000 psi pressure generated when firing a .454 Casull revolver.

    Consistent with the difference in power, the larger caliber weapon has about 54% more recoil than the .44 mag. revolver.

    The prospects for success were not encouraging. Since the chambers in the cylinder had to be larger to accommodate the larger cartridge, some of the cross sections left between the chambers were reduced in thickness. These somewhat thinner walls had to withstand essentially 50% higher pressure than the original walls before redesign.

    Undaunted by the challenge, President William B. Ruger, Jr., instructed his design team to use the best materials available to make the six-shot .454 Casull handgun the latest success in the Ruger line of durable, large caliber revolvers.

    Ruger first tried making the cylinder from stainless Type 410, a hardenable martensitic stainless steel generally suitable for highly stressed parts, such as Ruger's other revolvers. This grade simply would not hold up for any extended length of time during firing of the higher pressure proof rounds required for the .454 Casull.

    The company then asked Humberto Raposo, a regional metallurgist from Carpenter Technology Corporation (NYSE:CRS) for assistance in selecting materials. He suggested that Ruger consider Carpenter's new Custom 465® stainless.

    Custom 465 stainless, developed as a candidate for aerospace components, is a premium-melted, martensitic, age-hardenable alloy capable of about 260 ksi ultimate tensile strength when peak aged. In this condition, it also offers higher notch tensile strength and fracture toughness than other precipitation-hardening stainless grades. It provides, in addition, excellent resistance to stress corrosion cracking.

    Ruger made a cylinder from Custom 465 stainless, then fired 50 proof rounds from each of six chambers (total 300 rounds) at 92,000 psi. This is about 50% higher stress than that produced under actual firing conditions. The designers repeated this firing cycle numerous times and noted that the cylinder successfully withstood all of the proof firing without a scratch or sign of defect anywhere.

    With this evidence, Ruger selected the Carpenter alloy for the chamber of its new six-round .454 Casull. No problems related to cylinder materials have been reported to Ruger from the field since the mighty revolver was introduced a year ago.

    Ruger manufacturing personnel started with annealed, cutoff lengths of 1.875" bar stock from Carpenter, but found that the material had such clean microstructure that they could reduce its diameter requirements to 1.828", and save on material costs. A slight amount of OD turning and drilling of the pivot hole was done on a CNC screw machine.

    A CNC horizontal mill was used to drill all of the chambers. Ruger held tolerance of 0.002" on the ID of the chamber holes and 0.001" on alignment of the holes to the cylinder latch cut.

    Machinists achieved a good finish inside the reamed chamber holes. The finish obtained was so good, in fact, that the company has even considered eliminating the final roller burnishing operation.

    After machining, Ruger heat treated the cylinders in accordance with the schedule suggested by Carpenter to optimize essential mechanical properties, particularly strength and toughness.

    Nominal chemical composition of Custom 465 stainless steel is: carbon 0.02% max., manganese 0.25% max., phosphorous 0.015% max., sulfur 0.010% max., silicon 0.25% max., chromium 11.0/12.5%, nickel 10.75/11.25. titanium 1.50/1.80%, molybdenum 0.75/1.25%.

    The Barrel
    Ruger had to deal with several increased power issues in designing the barrel for its new .454 Casull revolver. Designers were concerned with the throat erosion that might occur when the big cartridge would exit the chamber and slam into the interior surface of the barrel. They knew the higher velocity bullet would have greater impact force, causing high-velocity gas cutting and potential erosion problems. That potential could be magnified if the steel selected for the barrel did not have the correct microstructure for these new requirements.

    The first material considered was stainless Type 410, the standard alloy used with great success for other revolvers in the Ruger line of revolvers. Ruger was able to gun drill a 0.480" dia. hole in a 1¼" OD x 19" long bar in 17.27 minutes at 1.1 IPM. However, the material was unable to meet the newer, more strenuous requirements for strength, ductility and corrosion resistance imposed by the higher pressure .454 Casull cartridge.

    Ruger then tried 15Cr-5Ni stainless steel, which met all the design requirements but one. It was a "bear" to machine. It took 28 minutes to drill the same diameter hole through the same OD bar at the slower rate of 0.71 IPM. The company could not accept the much longer gun drilling cycle time.

    Again, Ruger asked the same Carpenter metallurgist for assistance. He suggested trying Carpenter"s new Project 7000® 15Cr-5Ni stainless, which also has been used as an aerospace alloy, in place of the conventional 15-5 alloy.

    Carpenter Project 7000 15Cr-5Ni stainless is designed to offer improved machinability and with it, the opportunity to reduce part costs, cut cycle time and increase productivity. It has been made available as a "drop-in" replacement for the conventional 15-5 alloy in applications where improved machining productivity is desired.

    In its trial runs with the Carpenter alloy, Ruger found that it was able to reduce its gun drilling cycle time by 20%. The Project 7000 stainless grade from Carpenter, in fact, matched the cycle time of the stainless Type 410, while improving tool life significantly. The vacuum melted, PH stainless also has excellent transverse mechanical properties to resist the higher stresses produced by the new cartridge.

    The hole in the barrel, with a diameter tolerance of 0.002", is obtained by a deep hole drilling operation. The gun drilling is followed by reaming to obtain a finish. Each blank, starting at 1¼" OD x 19" long, is hammer-forged over a mandrel to become 1.171 OD x 23-7/16" long. The rifling and final diameter is formed during the hammer-forging. The forged length is then cut into three 7½"-long gun barrels.

    All barrels that had been made from the new Carpenter alloy passed Ruger's rigid endurance tests with flying colors.

    Typical analysis of Project 7000 15Cr-5Ni stainless is: carbon 0.07 max., manganese 1.00% max., silicon 1.00% max., phosphorus

    0.030% max., sulfur 0.015% max., chromium 14.00/15.50%, nickel 3.50/5.50%, copper 2.50/4.50%, molybdenum 0.50% max., columbium 5XC/0.45, tantalum 0.05% max., iron balance.

    * * *

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    Default Another interesting article on steels - Part 1

    I tried to paste the link but couldn't get it to work so here is the complete article. Charts weren't too good in the orginal either but show the general idea. It appears that 4340 would be an alloy to consider for a CS gun.

    Had to do this one in 2 parts due to limits on images.


    Selection of High Strength Stainless Steels for Aerospace, Military and Other Critical Applications

    </B>
    June 2006

    By Anthony Guitterez, member of ASM International
    Carpenter Technology Corp., Wyomissing, PA, USA
    High strength stainless steels and age-hardenable superalloys are rapidly gaining favor with designers in the aerospace, military and other industries who are challenged to meet higher performance expectations and stringent regulatory requirements at lowest life cycle cost.
    These specialty alloys are largely upgrades of conventional stainless steels and high strength alloy steels that are no longer able to meet the more demanding requirements of critical applications that keep growing in number and variety.
    Resistance to corrosion is of paramount concern since the costs of corrosion, with its material degradation, continue to escalate more than most realize. According to a recent study conducted by CC Technologies Laboratories, Inc., for the Federal Highway Administration (FHWA), the direct cost of corrosion in the U.S. is $279 billion dollars a year, or 3.2% of the nation's GDP. If one adds the indirect costs to the consumer the cost is doubled in terms of both dollars and GDP.
    Conventional stainless steels can provide the corrosion resistance needed for many demanding applications, but increasingly they lack the combination of high strength, toughness, fabricability and damage tolerance. Standard high-strength low-alloy steels (HSLA) may offer the high strength needed for some difficult applications but lack the corrosion resistance.
    Efforts to improve the corrosion resistance of high strength alloy steels with cadmium plating or other means of surface protection seem to be falling out of favor. This may be due to the growing, widespread objections to cadmium plating for environmental reasons, and the high costs of plating bath disposal. Furthermore, many recognize that surface treatment is not a viable, long-term solution to providing corrosion resistance nor achieving lowest possible life cycle costs.
    The high stakes in materials can be appreciated better when examining the needs of two pertinent industries, aerospace and military. With its landing gear hardware, wing assemblies and other airframe components made of high strength stainless steels, the aerospace industry must achieve superb performance, long term safety, reliability, durability and low life-cycle costs – in short, aircraft that will fly for 30 years with minimal maintenance.
    For its newer armed forces, the military seeks high performance alloys that will contribute to every major future platform with a focus on weight savings, improved corrosion resistance, higher strength while achieving lowest possible life cycle costs. The overriding objectives here are reliability and perpetual readiness (meaning no crippling rust from corrosion and ability to maintain peak mechanical performance).

    High Strength Stainless Steels
    An alloy is generally considered a high strength stainless steel when it meets several key requirements. First, it must have an ultimate tensile strength (UTS) of 225 ksi (1550 MPa) or more, and a minimum yield strength (YS) of 200 ksi (1378 MPa). Tensile ductility must be good, with a minimum 10% elongation preferred.
    To further qualify as a high strength stainless, the alloy generally exhibits fracture toughness as least as good as that of 15-5 PH stainless (S15500). It also must have general corrosion resistance similar to that of Type 304 stainless, with good resistance to stress corrosion cracking (SCC).
    Six Carpenter martensitic, precipitation (age) hardened (PH) stainless steels meet all the defined requirements. They are 15-5 PH stainless, Custom 450® stainless (S45000), Carpenter 13-8 (S13800), Custom 455® stainless (S45500), Custom 465® stainless (S46500) and the newest addition, Custom 475TM stainless. Their nominal chemical compositions are shown in Figure 1.
    Figure 1 – Nominal compositions of commonly used high strength stainless steels

    15-5 PH stainless

    Custom 450 stainless
    13-8 stainless
    Custom 455® stainless
    Custom 465® stainless
    Custom 475™ stainless
    Cr
    Ni
    Mo
    Co
    Ti
    Cb
    Cu
    Al
    15.0
    4.0
    --
    --
    --
    0.3
    3.5
    --
    14.8
    6.5
    0.8
    --
    --
    0.6
    1.5
    --
    12.7
    8.0
    2.3
    --
    --
    --
    --
    1.2
    11.5
    8.6
    --
    --
    1.3
    0.3
    2.2
    --
    12.0
    11.0
    1.0
    --
    1.7
    --
    --
    --
    11.0
    8.0
    5.0
    8.5
    --
    --
    --
    1.25

    Carpenter 15-5 PH stainless
    offers high strength and hardness, excellent corrosion resistance with good forgeability and transverse toughness. A drop-in variation of this alloy (Project 70+® 15Cr-5Ni stainless) meeting all 15Cr-5Ni specifications, offering improved machinability, has been used for the economical production of aircraft structural components.
    Custom 450 stainless combines the very good corrosion resistance of Type 304 with the moderate strength of Type 410 and is relatively easy to fabricate.
    Carpenter 13-8 stainless combines high strength and hardness with good levels of resistance to both general corrosion and stress corrosion cracking. Generally, this alloy should be considered where high strength, toughness, corrosion resistance and resistance to SCC are required in a steel showing minimal directionality in properties.
    Custom 455 stainless offers higher strength and hardness capability (about HRC 50) than Custom 450 stainless. It has good corrosion resistance coupled with ease of fabrication.
    Custom 465 stainless is a premium melted, martensitic, age hardenable alloy capable of 250 ksi (1724 MPa) UTS when aged at 950ºF (H950 condition) – which is 20% higher strength than possible with traditional stainless steels and is currently covered by the MMPDS–01, AMS 5936 and ASTM A564 specifications. The alloy also possesses excellent notch tensile strength and fracture toughness in this condition. Overaging to the H1000 condition provides a superior combination of strength, toughness and SCC resistance compared with other high strength PH stainless steels such as Custom 455 stainless and 13-8 stainless.
    Custom 475 stainless is Carpenter's newest premium melted, high strength, martensitic, precipitation hardenable stainless steel. It provides good corrosion resistance and was designed to achieve up to 290 ksi (2,000 MPa) UTS combined with good toughness and ductility when peak aged at 975ºF (H975 condition). Other combinations of strength, toughness and ductility are possible by applying aging temperatures up to 1100ºF. The alloy is currently available in strip, wire and small diameter bar.

    Major Considerations
    For many critical applications, the proper balance between an alloy's fracture toughness and specific strength is important. Figure 2, which includes Carpenter's ultra-high strength AerMet® 100 and 310 alloys, and a titanium grade, indicates that the combination of strength and toughness for Custom 465 stainless bridges the gap between the high strength steels and conventional stainless steels. Although not obvious from this chart, Custom 465 stainless exhibits 43% higher fracture toughness than Custom 455 stainless.
    Figure 2 - Relative range of fracture toughness and specific strength for high strength alloy steels and PH stainless steels

    The military and aerospace, among other sectors, would like to capitalize on the light weight advantages of metals like aluminum and titanium, to the extent permitted by strength requirements. One high strength stainless, Custom 465 stainless in particular, addresses the need for light weight. It offers a strength-to-weight ratio approaching that of titanium. Furthermore, it offers a still higher ratio capability in rolled strip, wire and small diameter bar.
    Custom 465 stainless excels in damage tolerance, an attribute coveted by the military and aerospace. This, in effect, is a measure of the alloy's ability to absorb energy and continue functioning in the presence of a failure. Materials specifiers have been willing, in some cases, to trade off strength to get more damage tolerance and corrosion resistance.
    Damage tolerance of various alloys is compared in Figure 3. The alloys are ranked based on the results of KIc (fracture toughness) and notch ductility tests. Custom 465 stainless in the H950 condition is rated second highest in damage tolerance, and Custom 455 stainless in the H950 condition is ranked sixth. AerMet 100 alloy, which is not a stainless steel, was ranked first in the study.

    Figure 3 – Ferrous-based and titanium alloys ranked by damage tolerance

    The PH stainless steels considered in this discussion all have superior combinations of tensile strength, fracture toughness, resistance to general corrosion and resistance to stress corrosion cracking (Figure 4). The 17Cr-4Ni PH stainless (S17400) is included in the bar chart because it is a good baseline alloy for comparison.
    Figure 4 – Relative strength, toughness, corrosion resistance and SCC resistance of key high strength, age-hardenable alloys

    Custom 465 stainless, the newest alloy in the group, is shown in the chart to have greater strength than any of the PH stainless steels. In fact, it can achieve more than 20% greater strength than the other PH stainless alloys shown. In addition, Custom 465 stainless has corrosion resistance clearly better than that of Custom 455 stainless, and equal to all the other grades in the series.
    Alloy Selection
    Carpenter has developed a simplified selection technique for choosing stainless steels known as the Selectaloy® method. It is a simplified approach to choosing the most suitable alloy for an application based on two criteria, corrosion resistance and strength. A brief explanation of this selection method may help in understanding how it works.
    The selection process begins after due consideration is given to life cycle costs rather than lowest initial cost – i.e. what's more important, the initial cost of the alloy or the cost of production/process failure or poor performance if the alloy choice is wrong?
    Then the materials specifier must determine how much corrosion resistance is needed, and how much strength is required for the specific application. Corrosion resistance increases from bottom to top of the vertical axis in the basic diagram (Figure 5), and strength increases from left to right along the horizontal axis.
    Figure 5 – Selectaloy® diagram showing relative corrosion resistance and strength of 14 stainless steels

    It is best to start with Type 304 stainless, the alloy specified more than 50% of the time when a stainless steel is needed. For greater corrosion resistance, move up sequentially to Type 316 or 20Cb-3® stainless. For less corrosion resistance, drop down to Type 430 or Type 409Cb.
    If more strength is needed at the lowest level of corrosion resistance, move to the right of Type 409Cb. Start with Type 410, then go progressively to Type 420, for more strength to Type 440A and for greatest strength to Type 440C.
    For more corrosion resistance, move up one level. If more strength is needed than that offered by Type 430, move right to Type 431 or Custom 455 stainless for greatest strength.
    If still more corrosion resistance is needed, move up to the third level. For more strength than that of Type 304, move right to Custom 450 stainless. For still more strength, continue moving right to Custom 465 stainless and Custom 475 stainless.
    The diagram now shows at a glance the relative corrosion resistance and strength of 13 commonly used stainless steels – including three of the high strength PH stainless steels highlighted in this article.
    Based on the same concept of relative values, a new Selectaloy® method and diagram (Figure 6) has been developed that compares the specific strength (UTS/density) and fracture toughness of pertinent alloys commonly used where very high strength is required.

    See Part 2 for remainder of article..

  18. #18
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    Default Another interesting article on steels - Part 2

    Here is the rest of the story....


    Figure 6 – Selectaloy® diagram comparing high strength alloys according to their relative fracture toughness and specific strength

    Custom 465 stainless and Custom 475 stainless join this small group of ultra-high strength steels. They bring not only high strength and corrosion resistance, but also fracture toughness better than that of all except AerMet 100 alloy.
    Positioning of the AerMet 100 alloy indicates that it offers the best combination of strength and toughness. AerMet 310 alloy provides the highest strength, with slightly less fracture toughness than its predecessor alloy. AerMet 310 alloy offers the ultimate high strength-to-weight ratio of this family of alloys.
    The well known 4340 and 300M ultra-high strength alloys have less strength than the two AerMet alloys and distinctly less fracture toughness than AerMet 100. The titanium grade, Ti 6-4, has an excellent strength-to-weight ratio, but lower fracture toughness than all the other steels shown. It is also a more expensive material.
    Applications
    Custom 465 was first specified in the aerospace industry for tension rods in the Joint Strike Fighter. It has since been approved for use in structural components such as flap tracks, slat tracks, actuators, engine mounts and landing gear hardware. With its certification and demonstrated performance, the stainless is being chosen by military and aerospace manufacturers for both new components and retrofit applications.
    Custom 465 stainless can be considered as a corrosion resistant replacement for 300M (which contains a slightly higher UTS but lower toughness), AISI 4340 and other similar types of steels typically used in high strength aerospace applications. It can also be considered as a higher strength replacement for stainless steels such as 15Cr-5Ni, 17Cr-4Ni and 13-8 stainless steels.
    It is the combination of high strength, toughness and corrosion resistance provided by Custom 465 stainless that convinced one aerospace company to use it for new torque tubes and flap tracks in lieu of other PH stainless steels and alloy steels. In one case, several structural parts for a new plane design required higher strength that that offered by the PH stainless steel that had been previously used in such applications. This same manufacturer has been evaluating the use of Custom 465 for flap tracks and flap carriages again because it matches the strength of the alloy steel currently used while also providing corrosion resistance.
    In general, Custom 465 stainless is less sensitive to process parameters than other high-strength PH steels. It's relatively low annealed yield strength, along with a low cold-work hardening rate, have made stainless well suited for producing fasteners and drawing small diameter wire. Another aerospace manufacturer, in fact, is considering Custom 465 stainless for aerospace fasteners because it has higher strength than both traditional PH stainless steels and many superalloys currently used for structural applications. In addition, the Carpenter grade has proven to be thermally stable after long-term exposure to elevated temperatures.
    * * *
    For technical alloy data on these and other Carpenter alloys, visit Carpenter's free, comprehensive technical information database.

  19. #19
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    Default

    It's a bit simplistic at best to say carbon steel is stronger than stainless steel.

    First you have to define what strength you are discussing, ultimate strength, yield strength, fatique strength, low temperature strength, high temperature strength, fracture strength, resistance to corrosion, resistance to erosion, etc,.

    And then one needs to define carbon steel vs stainless, as the top strength alloys are not simple alloys of iron and carbon on the one hand, and iron, carbon, chromium and nickel on the the other hand. And, exactly when is a steel stainless or not, as there are "non stainless" steels that have a fair bit of corrosion resistance, and stainless steels that are prone to corrosion.

    Finally the issue of heat treating and tempering has a huge affect on the physical properties of a given alloy.

    I have yet to hear of the failure of a stainless steel revolver when using loads appropriate for it's design. I also know of several blued ruger revolvers that have been blown up, due to running excessive loads.

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    Yeah, I like the way Paul said it.

    It looks like according to that article that the SRH 454 Barrels are made of the project 7000 steel which is 14/4 steel and not the 465 and 465 is used only for the cylinder and it is a 12/11 steel with Titanium. Hmmm.

    Well I dont think my guesses were very far off and I still see no evidence that "carbon" Chrome/Molybdenum steel is stronger than the stainless steel used today. This 465 is some tough stuff. There are many factors involved.

    Interesting. Also a tid bit of info. In the knife making world, a steel must have 14% chromium to be called stainless. From that angle 465 is not stainless, even though it is higher up on their corrosion resistance chart than the 410 thru 440C.

    I held stock in Carpenter for about 22 years because they were (and still are) a very progressive company, in was a good investment. I used to receive all there public announcements of their new steels and in 1999 when I sold out, there was no mention of the 465 steel. When did Ruger first make the SRH in 454?

    Nominal chemical composition of Custom 465 stainless steel is: carbon 0.02% max., manganese 0.25% max., phosphorous 0.015% max., sulfur 0.010% max., silicon 0.25% max., chromium 11.0/12.5%, nickel 10.75/11.25. titanium 1.50/1.80%, molybdenum 0.75/1.25%.
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