Procurement spec for 304 ss cold worked bar, ~34 - 39 HRC

[rollingcloud]

I have looked into ASTM A276 and AMS 5639, and neither specifies the desired hardness range. This question originated from a machining supplier. They can order standard 304 stainless steel per ASTM A276 or a similar specification in a cold-worked condition from a material vendor (~30HRC). However, the hardness would not meet our requirements, necessitating the machining supplier to increase the hardness through additional cold working. How feasible is it for them to achieve this consistently? (The final part is a rivet if that matters)

 

[MagBen]

do you mean consistently meeting hardness >30RC? very easy for 304 which can go over 90% reduction of cold work, hardness can go over 40RC. does ASTM A276 include a full/heavy hard condition?

 

[TugboatEng]

What is the diameter of the rivet? Can it be formed from wire? Wire is cold drawn and easily exceed your required strength.

17-4 PH has similar corrosion resistance and is commercially available at your required hardness.

 

[EdStainless]

If you want to see the cold work properties look at A666.
This is a sheet spec but the effects are similar.

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P.E. Metallurgy, consulting work welcomed

 

[rollingcloud]

MagBen,
Yes, >30 HRC.
ASTM A 276has a relatively severe cold worked condition. The tensile strength under this condition is 125 ksi.

 

[rollingcloud]

TugboatEng,
The head diameter is .22'', the body diameter is about .12''. Is the cutoff between bar and wire typically at .25''? that means it can be cold drawn from a .25'' wire, correct?

 

[rollingcloud]

EdStainless,
It looks like A666 has no round bar or wire options. But based on the 125 ksi tensile strength, its equivalent to 1/4 Hard under A666, and it has no hardness range for cold worked materials either, only the annealed section has specific hardness ranges.
It brings up another question, since A276 only says "cold finished", it does not mention if the material has been annealed or not, do we assume that it has only been cold worked under A276?

 

[rollingcloud]

Since the ASTM A276 requires a min tensile strength, is it really necessary to control the min hardness of the cold worked rivet? I feel like controlling the max hardness would be sufficient, since to achieve the requirement strength, one would need a specific hardness to make it happen?

 

[EdStainless]

You should have min and max UTS with min elongation.
Hardness will not tell you enough.

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P.E. Metallurgy, consulting work welcomed

 

[rollingcloud]

A276 only specifies the min UTS, min elongation, and min reduction in area. Condition B appear to be the highest UTS for 403SS. Is there any spec that requires a higher UTS or hardness than A276?

 

[MagBen]

Forget the name(s) of the spec, pretty sure i saw something min UTS 180ksi for full hard, >200ksi extra hard. 125ksi is kinda 1/2 hard. When the material goes to full, extra hard, the EL becomes very low, and YS is also high close to UTS.

There does not exist a size cutoff between bar and wire. bar products can be smaller than 0.25'', while wire can be more than 1.0''. Normally when the bar size is smaller than 1.0'', it is made out of wire, drawn to wire, then straighten and cut to bar form.

 

[EdStainless]

When you write your spec and list UTS range you also need to confirm how it is tested, you want full body tensile samples.

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P.E. Metallurgy, consulting work welcomed