Applications

• Superior corrosion resistance
• Almost double the yield strength
• Exceptionally low magnetic permeability
• Outstanding cryogenic properties : Outstanding corrosion resistance gives Armco's NITRONIC 50 Stainless Steel the leading edge for applications where Types 316. 316L, 317 and 317L are only marginal. It's an effective alloy for the petroleum, petrochemical, chemical, fertilizer, nuclear fuel recycling, pulp and paper, textile, food processing and marine industries.
• Components using the combination of excellent corrosion resistance and high strength currently include pumps, valves and fittings, fasteners, cables, chains, screens and wire cloth, marine hardware, boat and pump shafting, heat exchanger parts, springs and photographic equipment.
• Fastener - High strength, and higher strength fasteners can improve the durability of you equipment.
• Marine hardware - Mastings, tie downs
• Marine and Pump shafts - better corrosion than types 304 and 316, with double the yield strength.
• Valves and fittings - better corrosion than types 304 and 316, with double the yield strength.
• Downhole rigging - better corrosion than types 304, 316 and 17-4, with double the yield strength in annealed condition.
• Reduced cross sections - better corrosion than types 304, 316 and 17-4.

 

Chemistry

Annealing Temperature

NITRONIC 50 Stainless Steel can be supplied annealed at 1950 F to 2050 F (1066 C to 1121 C). For most applications, the 1950 F (1066 C) condition should be selected, as it provides a higher level of mechanical properties along with excellent corrosion resistance. When as-welded material is to be used in strongly corrosive media, the 2050 F (1121 C) condition should be specified in order to minimize the possibility of intergranular attack.

 

Corrosion Properties

Armco NITRONIC 50 Stainless Steel provides outstanding corrosion resistance - superior to Types 316, 316L, 317 and 317L in many media. For many applications the 1950 F (1066 C) annealed condition provides adequate corrosion resistance and a higher strength level. In very corrosive media or where material is to be used in the as-welded condition, the 2050 F (1121 C) annealed condition should be specified. High-Strength (HS) NITRONIC 50 bars are useful for applications such as shafting and bolting, but do not quite exhibit the corrosion resistance of the annealed conditions in all environments.

 

Intergranular Attack

The resistance to intergranular attack is excellent even when sensitized at 1250 F (675 C) for one hour to simulate the heat-affected zone of heavy weldments. Material annealed at 1950 F (1066 C) has very good resistance to intergranular attack for most applications. However, when thick sections are used in the as-welded condition in certain strongly corrosive media, the 2050 F (1121 C) condition gives optimum corrosion resistance.

 

Stress-Corrosion Cracking Resistance

In common with most stainless steels, under certain conditions, Armco NITRONIC 50 Stainless Steel may stress-corrosion crack in hot chloride environments. When tested in boiling 420/0 MgCI2 solution, a very accelerated test, NITRONIC 50 Stainless Steel is between types 304 and 316 stainless steels in resistance to cracking. There is little difference in susceptibility to cracking whether in the annealed, high-strength (HS), or cold-drawn conditions.

 

Sulfide Stress Cracking

Both laboratory tests and field service experience have shown that Armco NITRONIC 50 stainless has excellent resistance to sulfide stress cracking in air conditions. NITRONIC 50 in both the annealed and high-strength (hot rolled) conditions has been included in the 1996 revision of NACE Standard MR-01 -75' "Sulfide Stress Cracking Resistant Metallic Material for Oil Field Equipment," at hardness levels up to RC 35 maximum. The resistance to cracking in laboratory tests in synthetic sour-well solution(5% NaCI + 1⁄2% acetic acid. saturated with H2S).