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Default Steel for Olympic Barbell

As mentioned in the subject, I'm looking for steel suitable to be used to make an Olympic barbell, 2.2m long and 28mm in diameter. I'm torn between chrome-moly steel and spring steel. Again I'm not a metallurgist and know very little about these things. The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. I'm also looking for decent machining 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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Default Steel for Olympic Barbell

On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee
wrote:

As mentioned in the subject, I'm looking for steel suitable to be used to make an Olympic barbell, 2.2m long and 28mm in diameter. I'm torn between chrome-moly steel and spring steel. Again I'm not a metallurgist and know very little about these things. The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. I'm also looking for decent machining 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


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?

--
Ed Huntress
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Default Steel for Olympic Barbell

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

The bar will be at least 190000 psi tensile strength with 170000 psi yield strength.
Thanks


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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Default Steel for Olympic Barbell

On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee
wrote:

snip
The bar will be at least 190000 psi tensile st=
rength with 170000 psi yield strength.

/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


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"
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Default Steel for Olympic Barbell

On Sun, 09 Nov 2014 13:05:58 -0600, F. George McDuffee
wrote:

On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee
wrote:

snip
The bar will be at least 190000 psi tensile st=
rength with 170000 psi yield strength.

/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


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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Default Steel for Olympic Barbell

"Ignoramus16121" wrote in message
...

On 2014-11-09, wrote:
On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote:

The bar will be at least 190000 psi tensile strength with 170000 psi
yield strength.
Thanks


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.


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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Default Steel for Olympic Barbell

On Sun, 9 Nov 2014 15:20:59 -0500, "Carl Ijames"
wrote:

"Ignoramus16121" wrote in message
...

On 2014-11-09, wrote:
On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote:

The bar will be at least 190000 psi tensile strength with 170000 psi
yield strength.
Thanks


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.


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

===================================
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?


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"
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Default Steel for Olympic Barbell

On Sun, 9 Nov 2014 10:48:21 -0800 (PST), "
wrote:

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

The bar will be at least 190000 psi tensile strength with 170000 psi yield strength.
Thanks


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


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.
--
Cheers,

John B.
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Default Steel for Olympic Barbell

On Sun, 09 Nov 2014 19:49:09 -0600, F. George McDuffee
wrote:

On Sun, 9 Nov 2014 15:20:59 -0500, "Carl Ijames"
wrote:

"Ignoramus16121" wrote in message
...

On 2014-11-09, wrote:
On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote:

The bar will be at least 190000 psi tensile strength with 170000 psi
yield strength.
Thanks

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.


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

===================================
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?


Ive got an Olympic class bar with my weight set. Its solid bar stock.
Get a few hundred pounds on a hollow bar..its called a pipe..and it
will bend in a heartbeat.

Gunner

"At the core of liberalism is the spoiled child,
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosophy of sniveling brats."
PJ O'Rourke
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Default Steel for Olympic Barbell

Carl Ijames wrote:
"Ignoramus16121" wrote in message
...

On 2014-11-09, wrote:
On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote:

The bar will be at least 190000 psi tensile strength with 170000 psi
yield strength.
Thanks

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.


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





http://www.garage-gyms.com/olympic-b...ing-guide/#Oly

--
Steve W.
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Default Steel for Olympic Barbell

Ed Huntress wrote:
On Sun, 09 Nov 2014 13:05:58 -0600, F. George McDuffee
wrote:

On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee
wrote:

snip
The bar will be at least 190000 psi tensile st=
rength with 170000 psi yield strength.

/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


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


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.

--
Steve W.
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Default Steel for Olympic Barbell

On Mon, 10 Nov 2014 10:43:15 -0500, "Steve W."
wrote:

Ed Huntress wrote:
On Sun, 09 Nov 2014 13:05:58 -0600, F. George McDuffee
wrote:

On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee
wrote:

snip
The bar will be at least 190000 psi tensile st=
rength with 170000 psi yield strength.
/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


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


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.


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.

--
Ed Huntress


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Default Steel for Olympic Barbell

replying to Steve W. , Sandarpan Mukherjee wrote:
csr684 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.
--
Steve W.




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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Default Steel for Olympic Barbell

On Sat, 15 Nov 2014 18:18:01 +0000, Sandarpan Mukherjee
wrote:

replying to Steve W. , Sandarpan Mukherjee wrote:
csr684 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.
--
Steve W.




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


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/datashe...a46a1f1 eb1c3

Good luck!

--
Ed Huntress
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Default Steel for Olympic Barbell

replying to Ed Huntress , Sandarpan Mukherjee wrote:
huntres23 wrote:

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/datashe...a46a1f1 eb1c3
Good luck!
--
Ed Huntress




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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Default Steel for Olympic Barbell

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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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Default Steel for Olympic Barbell

On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


"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.

--
Ed Huntress


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Default Steel for Olympic Barbell

On Saturday, 22 November 2014 22:12:46 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


"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.

--
Ed Huntress


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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Default Steel for Olympic Barbell

On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


I'm more of a newb when it comes to metallurgy, but I think the
strength of the steel comes from the alloy, while brittleness comes
from the temper. Strong steels can be tempered for less brittleness,
which is what I think is happening in that bar. /opinion

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington
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Default Steel for Olympic Barbell

On Sat, 22 Nov 2014 10:09:21 -0800 (PST), Sandarpan Mukherjee
wrote:

On Saturday, 22 November 2014 22:12:46 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


"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.

--
Ed Huntress


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?


Hmmm. I'm rusty on a lot of this (no pun intended g). "Brittleness"
is not a term that metallurgists ordinarily use. They look at
elongation, and the gap between yield strength and ultimate tensile
strength. Charpy and Izod impact strength are additional terms. In
discussions of tool steels, you'll also see the term "timbre," which
is not well-defined.

What you're looking for, I think, is a determination of what happens
when the yield strength of the bar is exceeded. Does it bend, or does
it quickly reach the ultimate tensile strength, and snap? And if it
bends, how much does it bend before it snaps?

Right? If that's the case, I don't know the answer. I know that 5%
elongation suggests little bending before it snaps. As for thin versus
thick, that's a problem of mechanics: a 5% elongation in tension
allows more bending, in terms of degrees of bend, in a small wire
versus a thicker bar. So a smaller bar should bend more before
breaking than a larger one, all other properties being equal. This is
discussed in terms of the behavior of the "outermost fibers"
(theoretical) of a beam, including a wire or bar. It also explains why
a 300 kpsi piece of music wire will bend quite a lot before breaking.

I think. g Maybe someone who's more up to date on Statics and the
Strength of Materials (that's the title of a good book on the subject)
can chime in and correct me on this.

--
Ed Huntress
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Default Steel for Olympic Barbell

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin
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Default Steel for Olympic Barbell

On Saturday, November 22, 2014 11:42:46 AM UTC-5, Ed Huntress wrote:


"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.

--
Ed Huntress


I would think that 4130 would be a better choice than 4340.

Dan



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Default Steel for Olympic Barbell

On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin


The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.

--
Ed Huntress
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Posts: 13
Default Steel for Olympic Barbell

On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin


The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.

--
Ed Huntress


The actual load in the drop tests is easy to tell. Each plate is 45 lbs.
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Default Steel for Olympic Barbell

On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


I'm more of a newb when it comes to metallurgy, but I think the
strength of the steel comes from the alloy, while brittleness comes
from the temper. Strong steels can be tempered for less brittleness,
which is what I think is happening in that bar. /opinion

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington


Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation.
  #29   Report Post  
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Default Steel for Olympic Barbell

On Sunday, 23 November 2014 06:29:52 UTC+5:30, wrote:
On Saturday, November 22, 2014 11:42:46 AM UTC-5, Ed Huntress wrote:


"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.

--
Ed Huntress


I would think that 4130 would be a better choice than 4340.

Dan


Dan,

4130 doesn't meet my strength requirements. Remember, I need the bar to resist permanent deformation. That can be achieved only by high yield strength.. The standard is 200000 psi Tensile strength with ~ 180000 psi yield strength. Even then bars bend with abuse.
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Default Steel for Olympic Barbell

On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin


The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.

--
Ed Huntress


The actual load in the drop tests is easy to tell. Each plate is 45 lbs.


But that doesn't tell you what the load is on the bar, as a result of
being dropped with the weights on it.

For example, dropping it straight down and with the bar horizontal
imposes very little load on the bar.

Dropping it on a 45-degree angle to horizontal imposes a higher, but
unknown load. Note that the bar doesn't bend much in that test. The
load is not really very high, although it is more of an impact load.

--
Ed Huntress


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Default Steel for Olympic Barbell

On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?


I'm more of a newb when it comes to metallurgy, but I think the
strength of the steel comes from the alloy, while brittleness comes
from the temper. Strong steels can be tempered for less brittleness,
which is what I think is happening in that bar. /opinion

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington


Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation.


Yes, it's a balancing act of magic, metallurgically speaking.

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington
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Posts: 13
Default Steel for Olympic Barbell

On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin

The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.

--
Ed Huntress


The actual load in the drop tests is easy to tell. Each plate is 45 lbs.


But that doesn't tell you what the load is on the bar, as a result of
being dropped with the weights on it.

For example, dropping it straight down and with the bar horizontal
imposes very little load on the bar.

Dropping it on a 45-degree angle to horizontal imposes a higher, but
unknown load. Note that the bar doesn't bend much in that test. The
load is not really very high, although it is more of an impact load.

--
Ed Huntress


http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html

The above page gives approximate formulae to calculate impact stresses.
  #33   Report Post  
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Default Steel for Olympic Barbell

On Sunday, 23 November 2014 20:18:45 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

I'm more of a newb when it comes to metallurgy, but I think the
strength of the steel comes from the alloy, while brittleness comes
from the temper. Strong steels can be tempered for less brittleness,
which is what I think is happening in that bar. /opinion

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington


Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation.


Yes, it's a balancing act of magic, metallurgically speaking.

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington


Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell.
  #34   Report Post  
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Posts: 12,529
Default Steel for Olympic Barbell

On Sun, 23 Nov 2014 08:48:09 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin

The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.

--
Ed Huntress

The actual load in the drop tests is easy to tell. Each plate is 45 lbs.


But that doesn't tell you what the load is on the bar, as a result of
being dropped with the weights on it.

For example, dropping it straight down and with the bar horizontal
imposes very little load on the bar.

Dropping it on a 45-degree angle to horizontal imposes a higher, but
unknown load. Note that the bar doesn't bend much in that test. The
load is not really very high, although it is more of an impact load.

--
Ed Huntress


http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html

The above page gives approximate formulae to calculate impact stresses.


I really don't think that would answer it for you. When a bar is held
at 45 deg. to horizontal and dropped, the impact of the lower weights
is not transferred to the bar. It's absorbed by whatever is on the
ground.

The impact imposed by the upper weights depends on a complex set of
forces and deflections, which involve tracing the forces from the
upper weights, through the bar, to the lower weights, to where the
lower weights contact the ground.

Good luck with that. g

--
Ed Huntress
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Default Steel for Olympic Barbell

"Sandarpan Mukherjee" wrote in message
...
...
Yes. What I would love to know is though, what is the elongation %
and reduction in area of the bars at the given strength. Something
no manufacturer is willing to tell.


A failed, discarded bar might.

If you plan to make these things you need a way to proof test them
anyway.




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Default Steel for Olympic Barbell

On Sun, 23 Nov 2014 08:49:29 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 20:18:45 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

I'm more of a newb when it comes to metallurgy, but I think the
strength of the steel comes from the alloy, while brittleness comes
from the temper. Strong steels can be tempered for less brittleness,
which is what I think is happening in that bar. /opinion

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington

Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation.


Yes, it's a balancing act of magic, metallurgically speaking.

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington


Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell.


See Bethlehem Steel's "Modern Steels and Their Properties." This is a
scan minus the attribution:
http://www.akronsteeltreating.com/do...y/ast-book.pdf


--
Ned Simmons
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Default Steel for Olympic Barbell

On Sun, 23 Nov 2014 17:15:31 -0500, Ned Simmons
wrote:

On Sun, 23 Nov 2014 08:49:29 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 20:18:45 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

I'm more of a newb when it comes to metallurgy, but I think the
strength of the steel comes from the alloy, while brittleness comes
from the temper. Strong steels can be tempered for less brittleness,
which is what I think is happening in that bar. /opinion

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington

Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation.

Yes, it's a balancing act of magic, metallurgically speaking.

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington


Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell.


See Bethlehem Steel's "Modern Steels and Their Properties." This is a
scan minus the attribution:
http://www.akronsteeltreating.com/do...y/ast-book.pdf


Excellent! I see 202 pages of unexpected reading in my near future.
Link saved.

--
"Government is not reason; it is not eloquent; it is force.
Like fire, it is a dangerous servant and a fearful master."
--George Washington
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Default Steel for Olympic Barbell

On Sunday, 23 November 2014 22:44:13 UTC+5:30, Ed Huntress wrote:
On Sun, 23 Nov 2014 08:48:09 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin

The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.

--
Ed Huntress

The actual load in the drop tests is easy to tell. Each plate is 45 lbs.

But that doesn't tell you what the load is on the bar, as a result of
being dropped with the weights on it.

For example, dropping it straight down and with the bar horizontal
imposes very little load on the bar.

Dropping it on a 45-degree angle to horizontal imposes a higher, but
unknown load. Note that the bar doesn't bend much in that test. The
load is not really very high, although it is more of an impact load.

--
Ed Huntress


http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html

The above page gives approximate formulae to calculate impact stresses.


I really don't think that would answer it for you. When a bar is held
at 45 deg. to horizontal and dropped, the impact of the lower weights
is not transferred to the bar. It's absorbed by whatever is on the
ground.

The impact imposed by the upper weights depends on a complex set of
forces and deflections, which involve tracing the forces from the
upper weights, through the bar, to the lower weights, to where the
lower weights contact the ground.

Good luck with that. g

--
Ed Huntress


True, what you say, which is why I wrote approximate.
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Default Steel for Olympic Barbell

On Monday, 24 November 2014 00:09:02 UTC+5:30, Jim Wilkins wrote:
"Sandarpan Mukherjee" wrote in message
...
...
Yes. What I would love to know is though, what is the elongation %
and reduction in area of the bars at the given strength. Something
no manufacturer is willing to tell.


A failed, discarded bar might.

If you plan to make these things you need a way to proof test them
anyway.


And therein lies the problem. The driving force behind me wanting to make a bar in the first place is a complete lack of quality equipment in my country. Elite athletes all import Eleikos. However they are sponsored. I am not.
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Default Steel for Olympic Barbell

On Mon, 24 Nov 2014 07:31:14 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 22:44:13 UTC+5:30, Ed Huntress wrote:
On Sun, 23 Nov 2014 08:48:09 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee
wrote:

On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:

On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:

http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU

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?

"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.

Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.

Martin

The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.

--
Ed Huntress

The actual load in the drop tests is easy to tell. Each plate is 45 lbs.

But that doesn't tell you what the load is on the bar, as a result of
being dropped with the weights on it.

For example, dropping it straight down and with the bar horizontal
imposes very little load on the bar.

Dropping it on a 45-degree angle to horizontal imposes a higher, but
unknown load. Note that the bar doesn't bend much in that test. The
load is not really very high, although it is more of an impact load.

--
Ed Huntress

http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html

The above page gives approximate formulae to calculate impact stresses.


I really don't think that would answer it for you. When a bar is held
at 45 deg. to horizontal and dropped, the impact of the lower weights
is not transferred to the bar. It's absorbed by whatever is on the
ground.

The impact imposed by the upper weights depends on a complex set of
forces and deflections, which involve tracing the forces from the
upper weights, through the bar, to the lower weights, to where the
lower weights contact the ground.

Good luck with that. g

--
Ed Huntress


True, what you say, which is why I wrote approximate.


If you really want an engineering analysis of the loads and
deflections, this is a job for finite-element analysis (FEA). The
tools for doing that today are amazingly good. It would make a good
term paper for a mechanical engineering student.

However, what you have when you're done is a theoretical set of
behaviors based on nominal mechanical properties of the bar. You then
need to apply a safety factor, and that wouldn't be a piece of cake
for this job, either.

I don't know why you're making your own, but if I were doing it, I
would copy the material and dimensions of a commercial bar that is
known to be safe and successful. "Chrome-moly" is going to be 4340; I
would bet on it. But you could confirm it by asking the bar
manufacturer. I do that kind of thing all the time, as a writer in the
field. Most are forthcoming if it isn't about some proprietary issue,
and I can't imagine that this one is. They've publicly stated the
class of alloy; all you need to know is the last two numbers, which is
the carbon content. Again, that number is almost certainly 40.

Good luck with your project.

--
Ed Huntress
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