410SS ductile-to-brittle transition temperature (dbtt)

[yudhichen]

Hello everyone,

is there anyone know what is the 410SS DBTT value?
as i look at 4100SS mill cert to be used as a wellhead equipment (shall comply both API6A and NACE),
the material vendor guy said to me that 410SS cannot applicable to 'K' operating range (-75ºF), the min was only to 'P' (-20ºF)
since martensitic SS nature has poor impact value as the temperature decrease.

as far as i dig in google, i only found one s-curve (ductile to brittle behaviour) of 410SS from 'stainless steel' by joseph r davis. those book provide some s-curve graph, but the sudden impact value drop doesnt seem so steep. as i know, 4100SS need to be tempered around 1300ºF±25ºF to reach 22HRC max as per NACE limit. CMIIW.

does anyone know what's the DBTT value of 410SS? or is there any research or some documentation about charphy s-curve graph that explain this toughness problem.

regards

yudhi

 

[OGMetEngr]

410 typically has low charpy impact values at lower temperatures than anywhere from 0F to -50F, depending on strength level. Here's a link to typical values, look on page 7:

http://www.aksteel.com/pdf/markets_products/stainless/martensitic/410Cb PDB.pdf

A good choice similar to 410 but with much better low temperature impact properties is F6NM, as this alloy has nickel added to increase toughness at low temps.

 

[EdStainless]

Also you need to know if it is 410 (martensitic) or 410S (ferritic).

In the ferritic grades you need to know N + C, grain size, and thickness. It is rate for any of them to have useful toughness below room temp when they are over 0.125" thick.

In the martensitic versions you need to be aware of the heat treatment, the level of carbides, retained austenite, and tempering all have an influence on toughness.
The Ni modified alloys are commonly used when toughness or uniform properties in heavy sections are required.

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