Steel for Olympic Barbell

As mentioned in the subject, I'm looking for steel suitable to be used to m ake an Olympic barbell, 2.2m long and 28mm in diameter. I'm torn between ch
rome-moly steel and spring steel. Again I'm not a metallurgist and know ver y little about these things. The bar will be at least 190000 psi tensile st rength with 170000 psi yield strength. I'm also looking for decent machinin g characteristics so that I can put a knurl on it and cut grooves to attach sleeves.
Here are some steels I've thought about
SAE 4340 (Heat treated to the required Tensile strength) SAE 4140 EN 47??
Thanks
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On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee

Those are extraordinarily high strength requirements. No steel hardened to those levels will be easy to machine; probably near-impossible to knurl.
You can machine it in a normalized or annealed state, and then have it heat-treated. But are you sure you need that level of strength? What kind of load will be put on it to require that much strength?
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Ed Huntress

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On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote:

I can not imagine needing that kind of strength for something that a human in going to use. What diameter is the bar? What is the maximum weight that is going to be on the bar? My guess is that an ordinary barbell is made of something like A36.
Dan
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It is a thin bar, holding possibly 500 lbs on ends, held possibly in almost one point.
i
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On Sun, 09 Nov 2014 13:31:30 -0600, Ignoramus16121

I get 1,026 total pounds of weights to reach yield strength. You're a good guesser, Ig.
I think. I had to convert it all to inches, because I get screwed up using metric units for force -- kilogram-force versus Newtons.
So don't count on it.
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"Ignoramus16121" wrote in message wrote:

It is a thin bar, holding possibly 500 lbs on ends, held possibly in almost one point.
i ===============================================================================Just for grins I ran the numbers for a bar 2.2 m long 28 mm dia simply supported at the ends with 1000 lbs concentrated at the center. That is equivalent to supporting the bar at the center and putting 500 lbs at the very end of each side. The deflection at the center if the bar doesn't yield will be 6.44 inches and the maximum stress will be 165,000 psi. I'll never stress a bar that much (at least not using just one hand :-) :-) :-)), but depending on the actual weight (one poster said about 300 kg as a reasonable max which is 660 lbs), and adding in some margin of safety since it will be a live load (3x? like a floor or deck that people walk on), the OP's specs aren't unreasonable as goals and may be low. In reality the center of gravity of the weights will be at least 8-10" from each end, and the lifts with maximum weight will be with two hands probably 24" apart. Using those dimensions (bar 20" shorter supported in two places 24" apart) and 500 lbs at each end gives much more reasonable results, max deflection 2.4" at the center and max stress of 81,000 psi. The real win would be going up in diameter; even 32 mm (1.26") makes the bar 1.7 times stiffer and stronger. If this is a custom bar aimed at world record weights, I think it is reasonable to assume adult-sized hands so think about making the bar bigger unless some sanctioning body has a rule specifying the dimensions. If you can't make it bigger, at least try to squeeze the weights as close to the center as you can.
----- Regards, Carl Ijames
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On Sun, 9 Nov 2014 15:20:59 -0500, "Carl Ijames"

==================================Anything to be gained by pre stressing the bar [assuming it is hollow] by putting some sort of tensioning device in the center such as a high strength (1/2"?) steel rod w/tensioning nuts on the end caps?
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Unka' George

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Carl Ijames wrote:

http://www.garage-gyms.com/olympic-barbell-review-shopping-guide/#Oly
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On 11/9/2014 1:31 PM, Ignoramus16121 wrote:

And as you might recall - snatching one and press it to the top and let it fall to the ground. Hitting one end and crunch.
Martin
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On Sun, 9 Nov 2014 10:48:21 -0800 (PST), " snipped-for-privacy@krl.org"

The top end Olympic lifting bars (Elieko) are said to be 215,000 psi tensile strength steel and are heat treated. They claim to test their7 bars in a jig that loads them to 1,500 Kg. (3,306 Lb.) and the bar must withstand that without taking a permanent set.
The Men's standard bar is 2.2 M (7.2 ft.) long, the center section is 28 mm (1.1") with a "sleeve" on each end that is 415mm (16.3") long by 50 mm (1.968") in diameter. the sleeves are mounted on bearings so that when lifting the weights do not apply any torque to the center section where the bar is gripped. the complete bar weighs 20 Kg.
A quick look seems to show that Hossein Rezazadeh, an Iranian, holds the record at a total weight lifted, in the two events, of 472 Kg, The Clean & Jerk record is 363 kg. and the Snatch record is 214 kg.
The maximum that a human can bend over and pickup (Dead Lift) seems to be in the neighborhood of 460 Kg. or 1014 lbs.
--
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John B.
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On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee

</snip>
You are talking about very expensive HY210 submarine hull steel. I don't know if this is available in the civilian market.
These specs seem excessive for even Olympic class lifters. A quick google search indicates less than 300Kg for any single lift. http://tinyurl.com/lmoxl6a
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On Sun, 09 Nov 2014 13:05:58 -0600, F. George McDuffee

He's around the high end for heat-treated 4340. The thing is, with yield of 170 kpsi and ultimate tensile of 190, when that bar is overloaded, it's going to go "Bang!"
It doesn't sound like something you'd want in a barbell. <g>
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Ed Huntress wrote:

Actually his numbers are at the minimum that are allowed in an Olympic bar. The lower end bars are 170K tensile. The good ones are up around 210K!
The idea is that the bar has to flex when you lift, that helps you by storing energy that helps you flip during the lift. The bars also have bearing inside the weight sleeves so that as you lift the plates don't apply any torque to the bar and spoil the lift.
I have friends who lift HEAVY and most seem to use Eleiko, York or Werksan bars. They are not cheap but they do seem to last.
When they do clean/jerk lifts that bar looks like a wet noodle.
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wrote:

That's really pushing what you can do without really good material specification and very expert heat treating. You can get the ultimate tensile strength, but avoiding brittleness at that level of tensile strength is a job for the experts.
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replying to Steve W. , Sandarpan Mukherjee wrote:

What you are saying is absolutely true. This link ebay. co m.au/itm/F-OLB-Force-USA-Olympic-Lifting-Bar-20-Kg-Cross-Fit-Warranted-for-Crossfit-Use-/321487232831 (delete the spaces) advertises a bar of 216000 psi TS and it's mentioned that the bar is made from SCM 440 (same as AISI 4140) heat treated steel. What's bothering me is the hardness. Firstly I want to machine the bar and I also don't want it to be too brittle. Even if the yield strength is exceeded, I want the bar to bend not break.
Thanks
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On Sat, 15 Nov 2014 18:18:01 +0000, Sandarpan Mukherjee

It's not easy to find specific elongation properties of 4140 when it's heat-treated to 216 kpsi tensile. At the extreme end, 285,000 psi, elongation is 11% and machineability is 65%. Hardness is 578 Brinell or Rc 55.
That's more machineable than I expected, although it's carbide-only at 285 kpsi, and I didn't even know that it could develop 285 kpsi tensile strength. That kind of tensile strength, in diameters larger than wire, usually is associated with fairly brittle specialty steels and very low elongation.
So, at 216,000, elongation can be expected to be over 11%. That's not terrible. It shouldn't be inclined to break as soon as the yield strength is exceeded.
The thing is, heat-treating sounds tricky -- normalize, reheat for time, oil-qnench and extended temper -- and it probably requires real expertise to achieve those extreme properties without brittleness. You can buy it normalized but the time/temperature sounds like a job for carefully controlled furnaces.
http://www.matweb.com/search/datasheet.aspx?MatGUID 87bc1cf20343b985b1a46a1f1eb1c3
Good luck!
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replying to Ed Huntress , Sandarpan Mukherjee wrote:

http://www.matweb.com/search/datasheet.aspx?MatGUID 87bc1cf20343b985b1a46a1f1eb1c3

Thanks Ed,
At this point I'm not overly concerned with heat treatment procedures. Heat treatment in general is a tricky thing. I am just trying to zero in on the actual material.
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(Amazon.com product link shortened)
The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application?
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On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee

"Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%.
Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar.
--
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On Saturday, 22 November 2014 22:12:46 UTC+5:30, Ed Huntress wrote:

Also as far as I can tell from my decaying memories of Strength of Materials 101, thicker materials are more brittle than the same material when thinner? Especially high carbon steels. Is that correct?
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