superior spring (leaf spring) materials to 17-7 ch900

[mpiotr]

Hello all,

Do you have any suggestions for alternate spring materials, in sheet of plate form, with superior or similar properties to 17-7 ch900? Any material options are welcome. Titanium, composite, etc.
Thanks

 

[TVP]

By properties do you mean mechanical properties such as ultimate tensile strength? Fatigue strength? Corrosion resistance? Resistance to high temperatures (creep, stress relaxation)?

 

[mpiotr]

Definately structural properties - ultimate/yield tensile strength, fatigue is very important as this is for a spring application.
Intrisnic properties are less of a factor.

 

[israelkk]

If you can define your real problem it will be easier to answer your question.

https://sites.google.com/site/israelkk/home

 

[mpiotr]

Well its a leaf spring, approximate size 1.250"x2.000".
At this point its designed with 17-7 ch900. Lookng to up the displacement on the spring so in order to meet sress/fatigue I woulk like to investigate alternate materials in order to not change the envelope.
Just looking for spring material options here in plate or sheet form, that's all.
I've seen composite and titanium leaf springs in automotive racing applications hence Im asking.

 

[israelkk]

Is this leaf spring loaded to one direction or both directions? If it is for one direction you may be able to stay with 17-7CH900 but more information is needed:

1. Load and deflection desired?
2. Strip thickness?
3. Actual design and support fixing

You can try to look for Elgiloy (has higher strength for strip thickness below 1.2 mm).

 

[mpiotr]

I'm not looking for help designing a spring. I am looking for alternate materials that can be used in a leaf spring application.
Definately will look into Elgiloy, thank you for the suggestion.

 

[israelkk]

Calculating stresses and deflection from analytic formulations and FEA can take you only up to some point. However, in addition, there are processes that can increase the "static" force available from same leaf spring by almost up to 50%. However, it depends on the type of operation and the actual design. This of course will have a positive effect on fatigue life too.

 

[drawoh]

mpiotr,

I have considered titanium as the material for a pre-loader spring. The advantage of titanium is that it has a yield stress equivalent to spring steel, and a much lower elastic modulus. In an application with a given deflection, titanium will see a lower stress. The titanium spring can be deflected more than a steel spring.

I wound up calling up beryllium copper, which has yield stress and elastic modulus similar to titanium, but it appeared to be cheaper and more available. When the spring failed, I tested it with a current and ammeter, and it turned out to be pure copper, not beryllium copper.

What are you doing with your spring?

Do you have a source of titanium, and is your fabricator willing to fabricate it?

Beryllium copper is similar to titanium unless you have problems with corrosion and/or high temperatures. In the absence of a harness tester, your electrical technicians can verify the material.

I have designed springs out of Delrin. Typically, I needed high deflection, and I required or was willing to tolerate low force. Our machine shop likes Delrin.

If you are not having problems with large deflections, I would stick with conventional materials.

JHG