Stainless Steel Yeild Strength 3

[dbrando]

I am looking for a non magnetic Stainless steel with a yeild strength greater than 800Mpa and a modulus of elasticity of around 200,000. Cost is a factor so I am looking for the most cost effective option. Any suggestions?

 

[Maui]

You will likely want to use an austenitic stainless steel if you need it to be non-magnetic. For a 201 stainless steel in the annealed condition, the modulus of elasticity is 28.6 ksi and the tensile strength is approximately 110 ksi. You can find these values here:

http://www.aksteel.com/pdf/markets_products/stainless/austenitic/201_data_sheet.pdf

You specified a [italic]yield[/italic] strength of 800 MPa which is equivalent to 116 ksi. This value exceeds the tensile strength for this alloy in the annealed condition. It can be cold worked to raise the tensile strength, but it becomes magnetic as it is cold worked. The values you specified will be very difficult to achieve for a non-magnetic stainless steel. Good luck.

Maui

 

[weldstan]

Maui,
28.6 million psi not ksi.

dbrando,
You need to look for another material - not stainless.

 

[Maui]

weldstan, correct.

 

[dbrando]

Thanks. Any suggestions for materials that could work? We looked into titanium however the cost is too high. Also the material will need to be able to be machined relatively easily.

 

[MagBen]

try Carpenter 21Cr-6Ni-9Mn, a high nitrogen strengthened, austenitic stainless. to meet the yield strength, it needs to be cold worked. cold work can only cause a little bit of ferromagnetism. permeability changes from 1.004Mu (annealed) to 1.02 Mu the most (cold worked).

 

[dbrando]

Would a ph stainless be a viable substitute to cold working?

 

[MagBen]

non-magentic rules out the majority of PH grades with a martensitic structure, while austentic PH grades could not meet your yield strength

 

[dbrando]

ok. Thanks for the help

 

[OGMetEngr]

One austenitic PH that could meet the strength is Gr660 (UNS S66286), however I'm not sure what level of "non-magnetic" this would be in after aging. SMYS is 105ksi in ASTM A453 but this grade can be had with yield strength higher than what you require. You'll have to do some digging on the level of magnetism you'll have after aging or cold-work/aging.

 

[Guest102023]

Have a look at the Nitronic series, they are high-strength austenitics, although I can't vouch for their non-magnetic characteristics.

The modulus of elasticity I can't help you with (and no one else here can either).

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[EdStainless]

21-6-9 is Nitronic 40, it will stay non-magnetic when cold worked.
It is your best bet.

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Plymouth Tube

 

[tbuelna]

dbrando-

What will this material be used for?

You said ease of machining is a concern, as is raw material cost. But the total cost of raw material, processing, machining, etc is what matters. For example, you might be better off starting with a forged blank of a more expensive material that reduces machining costs, but also provides better mechanical properties. EdStainless' suggestion of Nitronic 40 is good, but Nitronic 40 is only available in a limited size of bar stocks.

A better description of your application would be very helpful.

 

[dbrando]

tbuelna-

The application is a shaft within a high voltage relay. One end of the shaft is press fit into a AISI 12L14 low carbon steel, the other is attached to silver plated copper. The largest diameter of the shaft is 3.353 mm. The issue we are having is with attaching the end to the copper. The attachment method involves compressing a prong feature machined into the shaft. The prongs compress, are inserted into the copper, and then return to their original position. The material we are currently using, 303 Stainless, is yeilding when compressed.

 

[Maui]

dbrando, you're going to have to cold work Nitronic 40 quite a bit in order to achieve a yield strength of 116 ksi. The room temperature yield strength in the annealed condition is only 54 ksi. Nitronic 50 might be a better choice:

http://www.hpalloy.com/Alloys/brochures/Nitronic50-bullet.pdf

Maui

 

[dbrando]

For Nitronic 40 and 50, the data sheets I found show a Rockwell hardness around 90. Will material be too hard/brittle to flex in our application?

 

[EdStainless]

In the annealed condition they will be be less than 90RB.
With modest cold work (20% reduction) we hit 150ksi UTS/130ksi yield/24% elong in Nitronic 40.

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Plymouth Tube

 

[OGMetEngr]

The modulus won't be where you want it, but if you simply need the part to elastically deform more without yielding you could also go with a titanium alloy. Strength will be there, non-magnetic, low modulus so more strain prior to yielding. Ti-6Al-4V would be the choice there.