F6NM is a low–carbon martensitic stainless steel with basic corrosion resistance, good strength, good toughness and much better weldability than most martensitic grades of stainless steel.
Approximate Composition – 13% Cr, 4.0% Ni, 0.5% Mo ≤ 0.05% C (EN and ASTM standards vary in chemical composition).
This grade combines the following characteristics:
- Basic pitting and crevice corrosion resistance
- Moderate sulphide stress cracking resistance
- Good yield strength (520 to 800 MPa minimum in EN standard depending on heat treatment)
- Better toughness than most martensitic grades (one of only 2 martensitic grades with guaranteed sub-zero impact toughness in EN pressure standards)
- Good weldability compared to other martensitic grades. Still requires pre- and post-weld heat treatment
F6NM is martensitic grade of stainless steel with several important enhancements. The molybdenum addition gives an improved corrosion resistance. The low carbon gives much improved weldability and along with the nickel produces excellent toughness. The dominant use of this grade is in the oil and gas industry.
Applications which illustrate these features include:
Valve bodies, flanges, valve seats, oil field equipment, hydro-electric turbine systems, pumps, chemical process plant, pressure die casting.