ASME.BPVC.VIII.2-2019 choice of fatigue curves for Method B screening

[tigny]

In ASME.BPVC.VIII.2, 3.F.1.2 there are the following qualifications, when selecting fatigue curves to apply to materials:

(a) Carbon, Low Alloy, Series 4XX, High Alloy, and High Tensile Strength Steels for temperatures not exceeding 371°C

(b) Series 3XX High Alloy Steels, Nickel–Chromium–Iron Alloy, Nickel–Iron–Chromium Alloy, and Nickel–Copper Alloy for temperatures not exceeding 427°C

1) Do 17Cr-4Ni-4Cu, or 13Cr-4Ni composed steels fall under "High Tensile Strength Steels" (as stated in 3-F.1.2 a)) or "Nickel–Chromium–Iron" (as stated in 3-F.1.2 b))?
Any input about this would be appreciated. Are there pieces of information in the Code about this?

2)Does the "High Tensile Strength Steels" pertain to Carbon Steels only?

best regards,

 

[IdanPV]

Hello,
My two cents regarding question number 1:

I think you should not use 3-F.1.2(b).
The composed steels you mention are Precipitation-Hardening Stainless Steels so you may not use the curves for 3XX High Alloy.

Hope that's helps.

 

[tigny]

Hi IdanPV,

thank you for your answer.

The 17Cr-4Ni-4Cu is a PH steel indeed. I'm inclined to go to the (a) curve.
The 13Cr-4Ni is a martensitic chromium steel. Because of its high tensile strength I have doubt about this classification.

I anyway used the conservative assumption to make the screening with the 3-F.1.2)(a) curve.