Qualifying A4-70 bolt per ASME B31.3

[mrpsi]

Hello, I need to qualify a Stainless Steel A4-70 bolt (size M10) per ASME B31.3.

Per ISO3506-1, it is described as "Soft or Work Hardened" in Figure 1.
Per ISO3506-1 Table 2, Tensile (UTS) = 700 MPa = 101.5 KSI & Yield(YS) = 450 MPa = 65.3 KSI

Question:
how do we know whether it qualifies as "strain hardened" per ASME B31.3 302.3.2(a)(2) or can we use the higher allowable stresses in (a)(1) since there are two other grades (A4-80 & A4-100) which are stronger and presumably "more" fully strain/work hardened?

For comparison:
A193 B8M Cl.1 : UTS=75 KSI, YS=30 KSI (B31.3 uses 302.3.2(a)(1)
A4-70,ISO3506-1:UTS=101.5 KSI, YS=65.3 KSI
A19. B8M Cl.2 : UTS=110 KSI, YS=95 KSI (<=3/4") uses 302.3.2(a)(2)

Thank you very much in advance.

 

[EdStainless]

Isn't an A4-70 70ksi min?
This is obviously lightly strain hardened.

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P.E. Metallurgy, consulting work welcomed

 

[mrpsi]

Good morning EdStainless,
thank you for responding. Yes, you are right that it is "lightly strain hardened".

I noticed in ISO3506-1 there are other versions that are stronger, so then they would have more strain hardening.

So, per ASME B31.3 then, whether it is "lightly strain hardend" or "fully strain hardened", the fact that it is strain hardened at all requires the user to use ASME B31.3 302.3.2(a)(2). Would you agree with this statement?

For our calculations, we ended us using this approach. That is, using the lower 302.3.2(a)(2) values rather than the 302.3.2(a)(1). We were wondering if there was some allowance given in the B31.3 code for a "lightly strain hardened" material, but we couldn't find one.