Heat Treat Mild Steel to make spring 3

[Ankeet18]

Hey

I am looking into how to heat treat mild steel and turn it into a spring, where the metal, steel, will come back to its orginal shape....the spring is a 5 sided spring where it is bent to make a pentagon type of shape

Thanks in advace for your help

Ankeet

 

[desertfox]

Hi Ankeet18

The only heat treatments you can do on Mild Steel is anneal,
normalize or stress relieve you cannot harden and temper it
which is probably what your thinking of to get your spring.
You need a spring steel for your application so you can improve the mechanical properties by heat treatment.
However material selection is subject to its service conditions ie enviroment, frequency of operation, forces etc. Can you give more details of the spring and its service conditions, details of the spring should include
dimensions, physical deflection required of the spring and
expected forces at given deflections and spring rate.

regards desertfox

 

[Ankeet18]

Hi

So I must have spring steel? There is not way to do it with mild, or any other form of steel

The "spring" is not a spring in the normal sense w/ coils, like a car spring, it is a steel bend into a pentagon looking part, each side is aprx. 1.3 in., the purpose of it is to keep a rotating part inside a housing, it needs to be able to keep tension so it does not fall out of the housing, but also be able to be removed and put back in, thus needed spring properties, what methods of heat treat you think would help me if I where to use spring steel, or any other steel.

Ankeet

 

[unclesyd]

You didn't say what diameter, but if you could get a piece of a 300 series SS welding wire of the needed diameter it would work. Just make it slightly larger than you need so that you have to compress it to fit the daimeter. Do forget to leave enough end gap.

A good hardware store will have several types of internal retaing rings that will do the same job.

 

[Ankeet18]

Hey

Its a flat metal that is 2mm high, and 4 mm wide that needs to be made, and no hardware store has it...

 

[rmw]

This is not scientific, but it is something that has stuck with me since I read it as a teenager.

If you read the book "Stalag Luft 13", (I think, going from over 40 year old memory, the book on which the movie, "The great escape" starring Steve McQueen was based,) you will find a passage where it describes that to make wire cutters, they would take mild steel strap material, which was left over from the camp's construction, and which they could scrounge, (how I don't remember) and heat it red hot, and quickly plunge it into a bucket of pure sugar.

The metallurgists will have to tell you just what happened, metallurgically speaking, but it made the straps hard enough so that when fastented together with a bolt or pin, they made great fence cutters, which several allied airmen used to escape with.

Now, I only tell you that to say, there has to be an idea starter for you in there somewhere.

rmw

 

[desertfox]

Hi Ankeet18

Heat treatment can only be considered after selecting material, size, strength level, application conditions and desired spring characteristics.
What forces do you require to exert and what deflection of the spring to achieve these forces.
I understand that your spring is a shaped spring from flat material and is not like a convential spring however it still must have a spring stiffness.
At what point along the arms is the load applied to the spring as this will affect the spring rate, stress in the spring and spring deflection.
You need to design your spring and get the design parameters sorted before worrying about heat treatment, depending on the design you might not need to heat treat, this goes back to my earlier response relating to service conditions etc.

regards desertfox

 

[rnd2]

Believe it or not but try this test:
Get a rod of mild steel, say no more than 3/8" and heat it quickly with a oxy/fuel gas torch keeping a neutral to just carburising flame. Immediately, DO NOT WASTE A SECOND, swirl it continuously through water from bright orange/yellow heat until it is cold. It will harden.

 

[EdStainless]

Ankeet, DFox has it right. You really need to know what kind of properties you are looking for first. Perhaps a low carbon grade of steel will harden enough for you, if you need low strengths. Maybe you could use some cold finished material.
You need to estimate the strength level first.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[seth2]

On the easier side, can someone tell me the best way to take a basically flat spring and increase the tension by hardening?

The Italian made guns I am working on have the correct shape and size but don't give enough resistance for the trigger pull required.

Rather than buy a myriad of after-market looking for the correct "weight," I'd like to try to fix what I have.

Thanks,

Seth

 

[CoryPad]

When you say resistance, do you mean spring force? If so, this is an elastic property that won't vary significantly with heat treatment. If you mean fatigue resistance, then heat treatment may be helpful.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[strokersix]

Consider cold working the material. Low carbon drawn wire can reach impressive tensile strengths. I don't know if this applies to what you are attempting but I think it's worth mention.

 

[NickE]

What cory said. You cant significantly change bending stiffness using heattreat or mechanical work, even alloying will have little effect until the alloy content gets large.

Nick
I love materials science!

 

[seth2]

Cory-

Both are a factor. Spring force is what I need.
There have been some wire replacements that actually fatigue fracture less. And, although the wire lasts longer and maintains the same force, they feel "mushy" in use.

I think I'll have them re-cut one of material .0005 to .001 thicker and go from there.

Thanks,

Seth

 

[oblate]

Hi ankeet18

You say no hardware store has it -(2mm by 4mm)
Perhaps you could buy a piece of key steel.
Key steel comes in rectangular sections and can be purchased in small lengths as well. Perhaps there is something close to a 2mm by 4mm section.You could obtain that from an engineering supply store. As for the springyness part of your question, perhaps your pentagonal spring does not move far. If that is the case then the material may well have sufficient movement within its own elastic limit. I am thinking of something like a piston ring where there is a gap in the ring. If the ring is closed then you have a bigger problem.

Regards

Oblate

 

[oblate]

Let me try another suggestion.
If you are trying to do what I think you are doing then let me suggest a redesigned spring so that you can use a standard part.

Suppose you have an outer part:
- machine a round grove into that like so
( )

And you have an inner part:
- machine a round grouve into it like so
) (

Now get an ordinary coil spring with a thinnish wire.
Insert the spring into the outer grouve so that the spring is forced to touch ends and take on a torroidal shape.
(0 0)

Force the inner component into the center of this torroid with a twisting motion. The torroid will distort so that all coils are at a slant while you do this.
(0) (0)

Hopefully this suggestion works and actually centers whatever it is you are trying to center.

You may have the problem that the torroid only permits motion in one direction