F6NM 2

[learningman]

I am in the process of getting a new job as a Engineering Buyer in a company that manufactures parts for the Oil Industry. I need more knowledge on various types of metals.
The first question i have is What is the advantage of using F6NM the 2nd question is what is the difference between F6NM & 17/4PH also what is the main differences between AISI 413 & AISI 4140

 

[IRstuff]

Seems to me that you should be asking your own engineers about this.

TTFN

FAQ731-376

 

[loclot]

Grade F6NM is a martensitic stainless steel. The additions of Nickel and Molybdenum, which gives it excellent sub zero notch ductility, superior to other standard 13 Cr, 410 and 420 Mod martensitic stainless steels.

This steel is air hardening, with little danger of thick sections cracking during heat treatment.

In addition to limiting the maximum hardness allowed to 23 HRC max, NACE MR0175 imposes heat treatment temperature restrictions

17/4 PH is a precipitation hardening martensitic stainless steel, containing Copper. In the solution treated and doubled aged condition it has become the preferred alloy for Stems, Shafts, etc, and is used extensively in valve internals. High strength, including good properties up to 315°C (600°F) and excellent corrosion resistance (comparable to 304 austenitic stainless in many environments) makes this alloy extremely versatile.

In addition to limiting the hardness, NACE MR0175 restricts the age hardening cycles that can be applied to the alloy to two of the several available. NACE MR0175 only permits solution treatment, followed by double aging to either the H1150M condition 760°C (1400°F) / 620°C (1150°F) or the DH1150 condition 620°C (1150 °F) / 620°C (1150°F).

I am not sure what AISI 413 is, but AISI 4140 is a medium carbon alloy that contains chromium and molybdenum and may be heat treated. It is usually used for general purpose parts.