Will case hardening "stiffen" a bracket
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    Default Will case hardening "stiffen" a bracket

    I have some brackets that are not quite stiff enough to do what I want to do with them. The steel used to make them is very questionable but probably the cheapest that could possibly be purchased. My question is would case hardening them stiffen them up a bit. They are quite small and I don't want to make new ones. Case hardening would be quite simple using Kasenite. This is kind of a general question as well since there have been numerous occasions where I have had brackets, small truss rods etc. that I would like to make a little stiffer. I am not trying to make gold out of lead here I just want to make them somewhat serviceable. Thanks for any replies in advance.

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    Hardening something will not change it's "stiffness", but only improve its resistance to plastic deformation.
    See here: Young's modulus - Wikipedia, the free encyclopedia

    Benta

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    Thanks Benta. I was afraid of that. I do a lot of case hardening for pivot pins on backhoes and tractor buckets but I have never really tried it on something I was trying to stiffen, only for wear resistance. I appreciate your input.

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    Most junkyard steel is only A36 anyway, and just plain wont get very hard. Unless you dont want it to- then, there will be some weird amounts of "allowable" stuff in the melt that makes it get TOO hard.

    Bigger, thicker brackets are probably in your future.

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    Get it red hot, then soak it in a bucket full of ground up "little blue pills" (which for the life of me I can't remember the name of right now!!!!) It claims to make everything hard.

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    Quote Originally Posted by JoeE. View Post
    Get it red hot, then soak it in a bucket full of ground up "little blue pills" (which for the life of me I can't remember the name of right now!!!!) It claims to make everything hard.
    But only for 4 hours. Otherwise something is wrong and you have to call a doctor.

    -DU-

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    pretty sure he wants his brackets to stay hard well after the ol is done
    haha
    seriously though as Mr.Ries so succinctly put it, i see bigger brackets in your future

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    Quote Originally Posted by JoeE. View Post
    Get it red hot, then soak it in a bucket full of ground up "little blue pills" (which for the life of me I can't remember the name of right now!!!!) It claims to make everything hard.
    Viagra is only for people.

    Tom

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    Question for the engineers - If the modulus of elasticity is the same for all steels, and heat treating (hardening) doesn't change it, Why is a hardened pry bar stiffer than a soft one? Wouldn't the higher tensile and yield strength make his brackets more resistant to flex? Empirical experience and the logic conflict for me, I've been looking for an explanation for this.

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    Quote Originally Posted by Mud View Post
    Question for the engineers - If the modulus of elasticity is the same for all steels, and heat treating (hardening) doesn't change it, Why is a hardened pry bar stiffer than a soft one? Wouldn't the higher tensile and yield strength make his brackets more resistant to flex? Empirical experience and the logic conflict for me, I've been looking for an explanation for this.
    It's the difference between elasticity and yield strength.

    A plain steel and a hardened steel pry bar would bend/deflect about the same. But the soft steel bar would ultimately bend and take a permanent set with less force applied.

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    Got it. The hard bar will flex the same up to the point where the soft bar is ready to yield, and continue to flex and still return. So it seems stiffer.


    ...........

    But - I have a piece of 1/4" diameter rod about 18" long, non magnetic, tests at about 2 Rc, seems to be stainless steel. I can't flex it much holding it in my hands and pushing with my thumbs. The same size of 1018 I can spring quite a bit. What is the difference there? I'm trying to chose a pushrod material for a customer, to duplicate his sample.

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    Thanks for the replies guys. I already know about the little blue pills however. I have to take a half of one to keep from peeing on my shoes.

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    Quote Originally Posted by crossthread View Post
    Thanks for the replies guys. I already know about the little blue pills however. I have to take a half of one to keep from peeing on my shoes.
    Thanks for that 'pointer'.

    Otherwise, by the time we really need them we've usually forgotten WHY.
    Life gets more economical all 'round. But starvation of one kind or another always WAS cheap.

    As to the brackets, dunno if it fits the application of the OP in the least, but 'triangulation' with a diagonal or cross-brace, else flat-plate, has been far the better route for my needs than simply heavier stock, from shelf-supports to mini-box corner-braces.

    Bill

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    Okay I'm going to stick my neck out here and display my ignorance. I have a bunch of steel here in the shop. I have some that I know what it is like A1. O1 4140 etc. I also have a ton of mystery steel. Some of it is very stiff. Think push rod or valve stem. Some other is quite bendy. My question is does the chemical makeup of the steel determine the stiffness? I am not talking about hardness like in the Rockwell scale or for wear resistance but how bendy it is. Is most of the stiffness due to heat treating, chemical makeup or a combination of both? If it is heat treating then I would think I could heat up my brackets and quench them or something. I know this would not make them any harder without case hardening because there isn't enough carbon in the steel, Opinions?

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    If they are sheet metal then adding some indents along the fold can help: Sheet metal work stiffening bends | V and F Sheet Metal. If the brackets are machined from soft steel it might be possible to do the same thing.

    I'm not a metallurgist but wonder if the material isn't annealed and needs to be heated and quenched to bring it to its spec'd characteristics.

    Cheers,

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    Quote Originally Posted by crossthread View Post
    Okay I'm going to stick my neck out here and display my ignorance. I have a bunch of steel here in the shop. I have some that I know what it is like A1. O1 4140 etc. I also have a ton of mystery steel. Some of it is very stiff. Think push rod or valve stem. Some other is quite bendy. My question is does the chemical makeup of the steel determine the stiffness? I am not talking about hardness like in the Rockwell scale or for wear resistance but how bendy it is. Is most of the stiffness due to heat treating, chemical makeup or a combination of both? If it is heat treating then I would think I could heat up my brackets and quench them or something. I know this would not make them any harder without case hardening because there isn't enough carbon in the steel, Opinions?
    'Opinion' here is that your wishing-for is blinding you to facts on the ground.

    My older metallurgy textbooks date from Dad's 1920's university courses.

    Newer super-alloys and cryogenic treatments notwithstanding, the realities simply haven't changed for common steels, nor should one expect them to do. In nearly a hundred years now, we've actually gained far more in the OTHER direction - alloys that can take more bending without failure. Greater stiffness is the realm of the exotics. Think tungsten 'whiskers' and exotic carbon structures, not plain-Jane iron and steel.

    No magic.

    BTW - are your pushrods perchance tubular? The stiffest ones generally are, and even then, eliminating them outright with overhead-cams eventually trumps the best tricks available.

    No free lunch there, either. I've had FIAT 124 valve stems simply shatter like glass when a timing belt went walk-about and they met the pistons. Glad it wasn't an Alfa or Ferrari with sodium-filled exhaust valve stems.

    Adding; Still a non-believer? Simply slice yourself a test bracket out of a common through-body porcelain floor-tile. Note that it won't bend appreciably at all (it actually does, but damned hard to measure).

    What it will do, however .... is fail catastrophically. Not sure that should be considered an improvement, but it works well enough for coffee-cups and dinner-plates. Within their load-limits. As always.

    Bill
    Last edited by thermite; 07-26-2012 at 05:51 PM.

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    To the OP, heat treating your brackets with Cherry Red, Kasenite etc may well make them more serviceable depending on how you are using them. Try this quick experiment.

    Heat treat 2" of the end of a piece of 1" X .125" mild steel flat, keep the heat on it for 3 minutes or so. Put the flat in the vice, leave 1" of the untreated end sticking out and bend it over 90° with a hammer. No trouble at all doing that. Now try hammering over 1" of the treated end.....

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    If your brackets are made of stamped sheet metal,you will actually remove any work hardening that bending and forming them put into the brackets when you heat them up. A few thousanths of case hardening is not going to compensate for annealing the brackets,and they will come out weaker than when you started. Weld in a gusset to strengthen them.

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    Quote Originally Posted by gwilson View Post
    Weld in a gusset to strengthen them.
    For sure. Or simply purchase 'em ready-made that way in larger sizes, stamped triangular with foldover edges in smaller, castings small and large - even decorative - of similar shape if appropriate.

    Seriously doubt this is mankind's first-ever need along these lines, or HD, Lowes, and their ironmongery predecessors the past two hundred years and counting wouldn't have all of the above in stock...

    Bill

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    +2 on the gusset, haven't ever seen anything worthy at lowes or HD but there are places like this that have tons of variety and cheap, for less than your time is worth.
    gussets
    on a related note, i save a bunch of my 'triangular shaped' cut off's from the band saw, keep them in a wall bin in the fab area with the other builders hardware type stuff. i go to that bin regularly for a random gusset.


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