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Forged???

Discussion in 'Rifle Country' started by TimH, Apr 30, 2003.

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  1. jad0110

    jad0110 Member

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    Next time an anti says we are just a bunch of gun loving, stupid, ignorant hicks, I'm whipping this thread out!

    A great read everyone, I've really enjoyed it.
     
  2. Slamfire

    Slamfire Member

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    The metallurgical discussion is way beyond my education, but the question of which one is stronger, seems to me to be a cart before the horse question.

    How often does someone design something based only on the material considerations? I am certain you could design an action, setting as your primary design criteria, “optimization of forging properties”, but why do that? I would think other goals are more important: cost, weight, function, safety, vendor supply, tooling, production processes, just do the system engineering. What do you think are the five most important characteristics of a rifle action,? And what are you willing to pay to get that?

    If your number one goal is lightweight, then the solution can be radically different then if your number goal is safety. And if safety is not an issue, only cost, you can build a cheap gun out of PVC tubing, a rubber band loaded nail, and duct tape. It will be a one shot device though!

    The material choice and fabrication technique support the overall design, they are not the design, or the program will surely fail. If you have ever sat down and wrote a system requirements document, and then done the trades, you know you have to trade things off to get an acceptable design. Yes, material choices influence the design, fabrication influences the design, but so does human factors, reliablity, maintainabilty, interchangablity, size, weight, etc, etc, etc. But there is one thing that totally dominates all commerical designs, and that is cost.

    On the commercial market, you have to be price competitive or the market walks to the cheaper product. And of course you cannot ignore features. The automotive industry found that people will buy one $40,000 vehicle over another, just because of cup holders.

    I want to thank everyone for keeping the discussion civil and very interesting.
     
  3. daniel (australia)

    daniel (australia) Member

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    You ask me that as if you think they are different things…:scrutiny:

    Well, yeah, of course. What did you think?

    You see, if you take a piece of your medium carbon steel and cool it slowly from a high temperature (ie from the austenite phase) you’ll end up with a microstructure composed of pearlite and ferrite, depending on carbon content, as I said in my last post. It doesn’t matter whether the steel was forged or cast. In this condition it is said to be annealed (if furnace cooled) or normalised (if air cooled) and it is comparatively fairly soft but ductile, stress free, and reasonably easy to machine.

    Now whenever you want to - once you’re done machining it perhaps - you heat treat it by raising its temperature high enough to transform it all back to austenite, and then you quench, which is to say cool it so fast that ferrite and pearlite don’t have time to form again but instead you end up with a transformation to martensite, which is an extremely hard but brittle metastable phase at room temperature.

    Your steel is not much use in that condition though, as it is too brittle, so you temper, by raising the temperature again to an intermediate level (below the austenite transformation temperature) to allow a certain amount of decay of the martensite structure and thereby regain some degree of toughness, though at the expense of some loss of hardness – the degree of tempering depends on the balance of these properties you want in the finished article.

    BTW the process is reversible too: you can take your quenched and tempered article and heat it then slowly cool to end up back at pearlite + ferrite again, and vice versa.

    I thought I had answered it, but perhaps not directly enough.

    I had already given the example of the aircraft parts, which have in recent times reached the stage of being no longer subject to the “casting factor” of the past.

    In terms of rifle receivers though, relying on my old first edition of De Haas' Bolt Action Rifles I can give you this comparison: The weight of the Winchester Model 70 action is listed as 48 oz (45 oz in the Featherweight), the Mauser 98 as 45, Sako L61 44 oz, Brno ZKK600 43 oz and the Ruger 77 long action as 42 oz. (Perhaps someone with a more recent edition or other data could chime in with figures for some more recent designs)

    All of these actions are about the same size, and for the same sizes of cartridge. I would suggest that all have proved quite sufficiently strong and serviceable, and they’re all much the same weight (though the Ruger, with the investment cast receiver, bolt, and other parts, is in fact the lightest by a small margin :neener:) In practical terms then the answer to your question must be yes.

    It is however a bit of an oversimplification, and I think Slamfire makes a very good series of points. Bottom line though is that investment casting as a technique is well established as a process capable of producing an action just as strong, safe and serviceable as forging or milling from tube or bar stock.
     
  4. JohnBT

    JohnBT Member

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    Knowing next to nothing on the subject, I learned a lot from Bill Caldwell's posts in this 2002 thread. You can google his name for info on his custom knives and guns. John

    "Forged Frame, Cast Frame : View from the Hills"

    www.pistolsmith.com/viewtopic.php?t=7912

    Excerpt from one of his posts in his thread:

    "The so called forged frames should be called drop forged frames. Proper forging technique calls for heating the steel to a certain temperature, then hammering in a proper sequence and with varying strength hammer blows, until the steel cools to a temperature where hammering should be stopped. Then the steel is reheated and hammered again. This is repeated until desired shape and dimensions are reached. A skilled blacksmith can refine the grain structure and grain direction. No frames are forged this way. Frame forging is done by heating a chunk of steel, placing it in a die, a matching die is slammed into this, and this is the 1911 forged frame. A quick way to get the general shape of the frame. This doesn't do anything to help the steel, and unless stress relieved and annealed, the frame is loaded with stress. It will certainly move during machining and heat treating. If the steel was not at the proper temperature when the hammer falls, lots can happen. All bad. Too hot: giant and very weak and brittle grain structure. To cold: inclusions, cold shuts. Not a good foundation to build on. "
     
  5. Boston T. Party

    Boston T. Party Member

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    Yes, heating pearlite into austenite first, of course.
    I thought you meant skipping the austenite phase,
    and going from pearlite directly to martensite.

    ____________
    Regarding the weight issue, I found this:

    More later,
    Regards,
    Boston
     
  6. hubel458

    hubel458 Member

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    Boston- You're not comparing the same things. Those cast
    rods used in those different small and big block engines
    were not investment cast and properly heat treated like gun
    actions and other stuff is built nowadays. And we've busted all
    kinds from mickey mouse engines up to Packard PT boat engines.

    Above quote-the Winchester Model 70 action is listed as 48 oz (45 oz in the Featherweight), the Mauser 98 as 45, Sako L61 44 oz, Brno ZKK600 43 oz and the Ruger 77 long action as 42 oz.

    And the Ruger is strongest......Ed
     
  7. Boston T. Party

    Boston T. Party Member

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    Regarding the "Ruger 77 long action as 42 oz", that is likely the MkI
    given the 1st edition of Haas's book. What do the MkII actions weigh?
    I'm away from my library, so I cannot now check this.


    OK, Daniel, these near-net shape investment cast parts are:

    1) slowly cooled down to annealed (or normalized) pearlite/ferrite, then
    2) machined (if necessary) to net shape, then
    3) reheated back up to austenite transformation temp, then
    4) quenched into martensite, then
    5) tempered

    I follow that perfectly. I think we all do by now.

    However, assuming, arguendo, that when the molds were poured
    the carbons were (somehow) very nicely distributed in austenite
    solution, that carbon content later segregates in stage #1
    (as laminar cementite Fe3C strips in pearlite/ferrite).

    When that pearlite/ferrite is reheated into austenite, any previous
    quality carbon distribution (i.e., in the first austenite phase
    during the investment casting) is lost as this second austenite
    phase is derived from pearlite/ferrite (with its carbide segregated
    in cementite strips).

    And how are those carbides randomly distributed in the (second)
    austenite then?


    The second austenite solution has none of the benefits that the
    first austenite solution enjoyed, such as (you mentioned) of induction
    furnace churning, gating, pouring, or ultrasonic vibration. Near-net
    shape pearlite parts are simply reheated to austenite and then quenched
    into martensite. (Rather, it's re-melted but not re-stirred.)

    If you counter that such processes (induction furnace churning,
    gating, pouring, or ultrasonic vibration, etc.) are not necessary for
    a well-mixed second austenite solution, then why were such
    even done at all the first time during the original casting?

    I.e., if simply reheating pearlite into austenite #2 effectively "stirs" the
    solution, then why bother (very elaborately) stirring it in austenite #1?

    McClung's point has been that attempts to drive pearlite segregated
    carbides into austenite solution are notably unsuccessful.
    Hence,
    investment casting relying on austenite-->pearlite-->austenite-->martensite
    process will have, according to his thesis, segregated carbides in the
    grain boundaries. In short, mere heat treat of pearlite does not create
    a well-mixed austenite (#2) and thus you can't avoid carbide strings in
    your martensite.

    If you have specific countering evidence on this very issue, please post
    it because we've arrived (finally) at the very crux of the dispute.

    ___________
    hubel458, are you saying that those cast con-rods were sand
    vs. investment cast?


    You've been saying that anecdotally, but without any offered
    empirical evidence. Just because you claim to "know" that the
    Win M70 wouldn't have held up to that load your M77 withstood . . .
    does not make it so.

    Regards,
    Boston

     
  8. hubel458

    hubel458 Member

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    Ruger ran shear tests of bolt lugs/bolt seats and
    they were about 25% higher than what the strength of
    the lugs and seats would have calculated out with tensile and
    yield strengths of a forged action the same size.

    As for the rods, broken ones looked just like a
    maleable iron. The auto mfs I don't feel
    could set up to do the bother, all the steps, and
    slowdown of proper heat treatment Ed.
     
  9. Boston T. Party

    Boston T. Party Member

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    Would have calculated out?
    That's empirical evidence?
    Sounds pretty thin to me.

    btw, the strongest bolt-action that author Haas could find
    was an Arisaka. It was almost impossible to blow up.
    A forged steel action . . .

    Boston
     
  10. hubel458

    hubel458 Member

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    I'm reporting Rugers tests, and compared with the
    strength of forged based on the tensile and yield strength
    of same size forged bolts and actions others built it
    was stronger. Simple math, get the cross section of parts,
    apply the math using the strength of metals and it gives
    a result. Yes Arisaka is almost impossible to blow up,
    which is great, just like a Ruger is almost imposible to blow
    up. I've seen charts where properly made investment parts heat treated
    right had a tensile strengths over 300,000 lbs. So all the
    talk about what happens at boundary layers don't mean nothing.
    Investment with treating is more uniform through out,Making for
    higher strength. Ed
     
  11. daniel (australia)

    daniel (australia) Member

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    Boston

    How do they dream this stuff up? :rolleyes:

    Leaving the truly laughable to one side though, I thought I’d dealt with the conrods, several times. You aren’t comparing apples with apples, as the method of production is different: these rods they're talking about are or were usually cast in sand moulds, though the article you posted also describes something that sounds like pressure diecasting (?), not investment casting. Incidentally I note that the article describes experiments carried out in the 1960s and 70s - which was, um, rather a long time ago;). Where the cutting edge is for high-performance conrods nowadays is squeeze cast metal matrix composites.

    The other point you continue to miss (and it isn’t made very well in the article either) is that it is fatigue life not strength which is the determining performance factor in conrods. If you read the article more closely you’ll see that: as they point out your basic as-forged rod is not that great for serious high-performance either, but can be dramatically improved by surface machining, radiusing, peening and polishing, all techniques which actually make it no stronger at all, but dramatically increase fatigue life. Fatigue really isn’t anywhere near being a factor for a rifle receiver though.

    I’d be prepared to bet the difference isn’t enough to help you:neener: Anyway, the comparison remains valid, as the Mk I had investment cast receiver, bolt and sundry other parts. The differences between it and the Mk II aren't really material in this debate.

    First of all the carbide doesn’t “segregate”. It is contained within the grains of pearlite, very finely distributed. When you heat it up into the austenite range the crystal structure reorganises – in the solid state – and the carbide molecules are re-dissolved in that structure in solid solution. The molecules don’t have to diffuse far to do that, and diffuse they do, resulting in a nice uniform composition. In fact austenitising is a method also used for addressing any microsegregation of alloys in alloy steels.

    When you then quench this, the speed of cooling doesn’t allow the iron and carbon to diffuse back into the ferrite + pearlite structure – that is rather the point in fact. Instead the carbon is retained in the crystal lattice as an interstitial solid solution, giving rise to a wholly different set of properties such as high hardness etc.

    BTW (and not for the first time) the same mechanism is at work regardless of whether the steel was cast or forged.

    No, the “second” austenite solution is formed entirely in the solid state, by heating the steel from lower temperature, unlike the “first”, formed from nucleation and grain growth by cooling from liquid. When you are producing the casting from the liquid steel you are trying to ensure the liquid is well mixed, so as to avoid segregation or variation the composition in the casting. This is more an issue with really big castings btw, including the cast billets and slabs from which you get bar stock for forgings;).

    Now if you’ve done it properly though your comparatively small receiver casting will solidify as a nice uniform austenite and, with decreasing temperature, this will transform to ferrite and pearlite. In the case of this transformation the diffusion distances the carbon travels are pretty small though, and when you heat it up again the carbon just has to diffuse back these same small distances to dissolve into a new and at least equally uniform (if not even more uniform) austenite.

    which in the context of the alloys we're talking about is utter nonsense.

    Again, utter nonsense. For starters the carbide doesn’t form on grain boundaries in these hypoeutectoid steels but as lamellae in the pearlite structure in grains of pearlite. I’ve posted micrographs to show you this. The pearlite completely transforms to austenite when you heat it above the appropriate temperature, and when you quench the carbon molecules are trapped as an interstitial solid solution in the martensite.

    Not only that but forgings of these alloys undergo precisely the same cycle: they are forged in the austenitic condition at elevated temperature, normalised to form ferrite + pearlite so as to allow machining, and then back up to austentising temperature, quench to martensite and temper.

    If this idea you attribute to Mr McClung were correct you’d have the same issue with forgings then: you'd have a nice even structure upon forging, but all the carbide would "segregate out" on cooling to ferrite + pearlite, and you'd never redissolve it on subsequent heat and quench heat treatment. Ironically this would put us back on a level playing field again for castings v. forgings - if this theory wasn't so wrong. Surely you can see that?

    I’ve put up the "evidence". Where’s the evidence for your (or your mate’s) position?

    The weakest too: the “unsafe” Herter’s Plinker .22 Hornet:neener:
     
  12. Reyn

    Reyn Member

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    Is someone honestly seeking the truth here or just refusing to accept it?
     
  13. Matt-J2

    Matt-J2 Member

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    Every time I see the thread title on the page, I start thinking documents.

    After that, having read through this thread, I think of the symbol of the snake eating it's own tail.
     
  14. Slamfire

    Slamfire Member

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    .
    From Hatchers’s Notebook : Japanese 6.5 mm Arisaka, “appear to be made of ordinary carbon steel similar to SAE 1085”

    The ground zero for some of de Haas comments on the Arisaka came from a P.O. Ackley’s “Vol II Handbook for shooters and reloaders”. Mr. Ackley conducted blowup tests, of forged military actions, and made comparisons. The Arisaka was the strongest.

    Read Stuart Otteson’s Book, “The Bolt Action”. After you read Otteson’s book you will understand that the Arisaka breech was extremely strong, because it was designed to be extremely strong. The Japanese created a design which gave superior support to the cartridge case. Creating a better design allowed them to use cheap plain carbon steel as a material, with plenty of safety margin.

    The US used nickel steel in both the Springfield and the Enfield, in an attempt to improve on action strength. But chromium and nickel are rare strategic materials. The Japanese were able to design out those additives.

    To get back on my soap box, the Japanese action was strong because they designed it to be strong. There are tradeoff’s, but the Japanese did not design this action as a demonstration of “optimial forging properties”, rather, their design goal was to create a strong, safe and simple service rifle.

    Putting the materials or the fabrication process before the design is putting the cart before the horse. And an purposeless argument. It is design that creates a strong action.

    Surprising to me, was the Japanese heat treat. From Ackely’s book: “it is obvious that this receiver was not only carefully, but even elaborately heat treated”…”Its heat treatment appears to be superior the average Mauser, Springfield and Enfield”….”Differential hardening, such as used on the bolt and firing pin…..”

    Does anyone know of any modern actions that use differential hardening?! Maybe the Japanese used their famous sword smiths to heat treat their receivers, eh Gad!
     
    Last edited: Feb 4, 2008
  15. JohnBT

    JohnBT Member

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    The stuff I watch on my new HD tv. If cast is good enough for the CAT 797B it's good enough for me.

    I didn't know they have cast frames. They cast these half dozen huge pieces and weld them together. The truck will haul a load of approximately 380 tons.

    From the CAT site:

    Weights - Approximate

    Gross Machine Operating Weight
    1375000 lb

    Chassis Weight
    473600 lb

    Body Weight Range
    38 000 - 63 000 kg (84,000 - 140,000 lbs)

    [​IMG]
     
  16. Gewehr98

    Gewehr98 Member

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    The bottom line?

    How many investment-cast receivers have failed, compared to their forged counterparts?

    Akin to counting the number of angels that can dance on the head of a pin, methinks. :scrutiny:
     
  17. Boston T. Party

    Boston T. Party Member

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    Thanks for your reply, Daniel.

    All forgings?

    Are not some-many forged parts quenched directly into
    martensite (thus purposely avoiding the pearlite phase)
    and then slightly annealed for easier machining?


    Can you post any micrographs to support that?

    Regards,
    Boston
     
  18. Boston T. Party

    Boston T. Party Member

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    Update from Boston

    Having spoken to Ron Smith at length about all this at 2008 SHOT,
    I am obliged to relay the gist of the conversation here.

    Ron termed the overreliance upon forged steel as "Celtic/Druid bullsh*t"
    which floored me coming from such a master of forged steel gun parts
    and receivers. He said that cast steel receivers (as he pointed to one of his
    own M14s at the booth) could be manufactured to be just as strong as forged,
    ". . . but the problem is keeping your foundry honest" regarding quality of
    steel, molds, etc. He explained that cast steel parts need such stringent
    quality control (e.g., individual X-raying) that it makes more sense for some
    firms to make forged steel parts instead -- not for any advantage in strength
    but in reduction of QC costs.

    I then asked him if he had the same confidence in his cast M14 as he has
    in his forged M14, and replied that he did, especially after testing his cast
    M14 to the point of catastrophic failure (and it still held).

    Ron and Kevin McClung know each other (I introduced them) and are friends.
    Ron expressed sincere respect for Kevin's knifemaking skill and knowledge,
    but asked rhetorically "How many rifle receivers has he made?"

    When I earlier posted that:


    . . . it turns out that I'd misunderstood Ron's remark years ago in his shop when
    he examined my rifle, as he corrected me at SHOT that he was speaking
    of Springfield Armory's poor heat-treat vs. the cast receiver itself. This was
    my error, which I will retract in both Boston's Gun Bible and in this thread.
    I apologize for misreporting that point, and Daniel was entirely correct when he wrote:



    _________________
    When McClung emailed me in 2006:

    . . . it was sufficient for me to publish his thesis in Safari Dreams, but it can no longer
    stand alone as a pedestal for that thesis. While I personally still prefer a forged steel
    rifle receiver over cast, it's appearing that McClung's thesis so far has no outside
    engineering and metallurgical support. In the name of thoroughness I will still try find
    corroborating evidence for it, but by now it really is time that McClung himself step up
    and either successfully defend his own thesis or admit its flaws. Suffice to say that
    the first reprinting of Safari Dreams will be modified accordingly.

    Meanwhile, I thank Daniel and others here for their effort and patience during their many
    informative posts. It's been a most interesting thread.

    Boston
     
  19. JohnKSa

    JohnKSa Member

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    Let me be the first to commend you for your very impressive intellectual honesty in re-opening this thread to post this update and also to thank you for the information.
     
  20. Boston T. Party

    Boston T. Party Member

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    Thanks, John, it's very kind of you to say so.

    Boston
     
  21. Slamfire

    Slamfire Member

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    I'll second this. :D
     
  22. TimH

    TimH Member

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    Well I guess I'l third it since I'm the origanal autor of the thread
     
  23. Boston T. Party

    Boston T. Party Member

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    M1A barrel failure and KB

    Somewhat related to this thread, and interestingly
    it regards the failure of a roll-forged barrel because of poor heat-treating.

    I've quoted it below, but refer to the tech article for accompanying photos.

    The backstory of this KB at:
    http://www.thegunzone.com/m1akb.html

    Boston


    http://www.thegunzone.com/m1akb/762r.html
     
  24. gvnwst

    gvnwst Member

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    Dang, long going thread:what::eek:
     
  25. TimH

    TimH Member

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    [proud papa} Thats my baby [proud papa]
     
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