Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old October 14th 05, 01:21 AM
Jordan
 
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Default 4140 - heat treat?

I made a bolt for the kickstarter of a friend's motorbike, as the
standard ones always bend. Used 4140 high-tensile steel, but now
thinking it might be improved by heat treatment.
But I've virtually no experience with this process, so:

Does it make sense, given that there is a thread on the bolt?
Will scaling or warping change its size and shape?
Is it easy enough to do?

Thanks
Jordan

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Old October 14th 05, 03:59 AM
Harold and Susan Vordos
 
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Default 4140 - heat treat?


"Jordan" wrote in message
u...
I made a bolt for the kickstarter of a friend's motorbike, as the
standard ones always bend. Used 4140 high-tensile steel, but now
thinking it might be improved by heat treatment.
But I've virtually no experience with this process, so:

Does it make sense, given that there is a thread on the bolt?
Will scaling or warping change its size and shape?
Is it easy enough to do?

Thanks
Jordan


Yes, it's fairly easy to do, but without a controlled atmosphere furnace, or
stainless foil, your chance of not screwing it up is not good. For one,
when you heat and soak the part as prescribed, you'll experience some
decarburization, and scaling will pretty much ruin the surface. Warping
can be controlled somewhat by proper quenching, but even that can be filled
with surprises. Chrome moly can be heat treated by torch, but you'll
still experience considerable scaling. If you'd like to try, heat to
1525/1625 F, and quench only in oil. I don't have a clue regards drawing
it after quench. I've always had heat treat done by a certified heat treat
facility, of necessity.

A good choice for the job you did is to use some pre-heat treated 4140. As
I recall, it comes hardened to somewhere between 28 and 32 Rc-----tough, but
quite machineable.

Harold


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Old October 14th 05, 09:08 AM
Jordan
 
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Default 4140 - heat treat?

Thanks Harold.
After this info, I daren't try heat-treating it myself.
Your suggestion to use pre-h'treated steel is noted for future reference.

Jordan
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Old October 14th 05, 01:16 PM
Steve Smith
 
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Default 4140 - heat treat?



Harold and Susan Vordos wrote:

"Jordan" wrote in message
. au...


I made a bolt for the kickstarter of a friend's motorbike, as the
standard ones always bend. Used 4140 high-tensile steel, but now
thinking it might be improved by heat treatment.
But I've virtually no experience with this process, so:

Does it make sense, given that there is a thread on the bolt?
Will scaling or warping change its size and shape?
Is it easy enough to do?

Thanks
Jordan



Yes, it's fairly easy to do, but without a controlled atmosphere furnace, or
stainless foil, your chance of not screwing it up is not good. For one,
when you heat and soak the part as prescribed, you'll experience some
decarburization, and scaling will pretty much ruin the surface. Warping
can be controlled somewhat by proper quenching, but even that can be filled
with surprises. Chrome moly can be heat treated by torch, but you'll
still experience considerable scaling. If you'd like to try, heat to
1525/1625 F, and quench only in oil. I don't have a clue regards drawing
it after quench. I've always had heat treat done by a certified heat treat
facility, of necessity.

A good choice for the job you did is to use some pre-heat treated 4140. As
I recall, it comes hardened to somewhere between 28 and 32 Rc-----tough, but
quite machineable.

Harold


A useful trick is to rub soap (plain bar soap) over the metal surface.
It won't prevent discoloration and a small amount of oxidation, but it
will prevent any significant scaling. Depends on the item, try on a
spare piece first...

Steve
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Old October 15th 05, 02:21 AM
john
 
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Default 4140 - heat treat?



Jordan wrote:

I made a bolt for the kickstarter of a friend's motorbike, as the
standard ones always bend. Used 4140 high-tensile steel, but now
thinking it might be improved by heat treatment.
But I've virtually no experience with this process, so:

Does it make sense, given that there is a thread on the bolt?
Will scaling or warping change its size and shape?
Is it easy enough to do?

Thanks
Jordan




If you got an oxy/acytlene torch, a magnet, and a bucket of oil you can
easily heat treat it.

Set the torch with a reducing flame, one which there is an excess of
carbon. This will keep the metal from oxydizing. Heat the metal until
the magnet will not attract the steel. This is the point where the
steel changes...I forget what to what, but at that point you want to
quench the piece immediately. By the way, make sure you quenching oil
is about 140 degrees or the piece will chill too fast and crack. Also,
when you immerse the piece in the oil, do not pull it back out because
the smoke will flash and burn. Keep moving it while holding it under
the oil until it is cool. It will be in the full hardened condition,
for 4140 that will be about 56rc rockwell. Now you got to draw,
temper, anneal it, choose a word. What you do is to heat it back up to
about 600 degrees and then let it cool. 600 degrees is when the metal
turns a very light straw color. Sand off a place so you can see the
color change easily. I would practice on a piece first before you do a
finished piece.


John


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Old October 16th 05, 02:53 AM
Jordan
 
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Default 4140 - heat treat?

Wow, thanks John.
Sounds like alchemy!

Jordan


If you got an oxy/acytlene torch, a magnet, and a bucket of oil you can
easily heat treat it.

Set the torch with a reducing flame, one which there is an excess of
carbon. This will keep the metal from oxydizing. Heat the metal until
the magnet will not attract the steel. This is the point where the
steel changes...I forget what to what, but at that point you want to
quench the piece immediately. By the way, make sure you quenching oil
is about 140 degrees or the piece will chill too fast and crack. Also,
when you immerse the piece in the oil, do not pull it back out because
the smoke will flash and burn. Keep moving it while holding it under
the oil until it is cool. It will be in the full hardened condition,
for 4140 that will be about 56rc rockwell. Now you got to draw,
temper, anneal it, choose a word. What you do is to heat it back up to
about 600 degrees and then let it cool. 600 degrees is when the metal
turns a very light straw color. Sand off a place so you can see the
color change easily. I would practice on a piece first before you do a
finished piece.



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