NITRONIC® 50 (XM-19) High Strength 22-13-5 Marine Alloy (UNS S20910) Fe 57, Cr 22, Ni 13, Mn 5, Mo 2, Si 1 Description

NITRONIC® 50 (XM-19) (UNS S20910)
Fe 57, Cr 22, Ni 13, Mn 5, Mo 2, Si 1

Austenitic Stainless

NITRONIC 50 Stainless Steel provides a combination of corrosion resistance and strength not found in any other commercial material available in its price range. This austenitic stainless has corrosion resistance greater than that provided by Types 316 and 316L, plus approximately twice the yield strength at room temperature. In addition, Armco NITRONIC 50 Stainless has very good mechanical properties at both elevated and sub-zero temperatures. And, unlike many austenitic stainless steels, NITRONIC 50 does not become magnetic when cold worked.

High Performance Alloys can make hot rolled, cold worked, & strain hardened High Performance Stainless Steel (HPSS) bars in house. Ask for our GFM Bulletin for more information about our bar processing capabilities. We have expanded to enhance product availability.

Characteristics

High Strength (HS) Bar Properties

NITRONIC 50 stainless bars also are available in a high-strength condition attained by special processing techniques. The superior strength of NITRONIC 50 HS produced by hot-rolling is size dependent, approaching that of annealed bars with sizes over 3" diameter. Because its high strength is produced by mill processing, hot forging or welding operations cannot be performed on this material without loss of strength. High-strength bars produced by rotary forging-special practice may have somewhat reduced resistance to corrosion and sulfide stress cracking.

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 / Specification

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 + ½% acetic acid. saturated with H2S)

Machining

MACHINING DATA
Carbide tools are suggested for rates better than 50% of Type 304.
Machining Type	Suggested starting rates are:
Single Point turning :	Roughing - 0.15" depth, 0.015"/rev feed -175 SFM Finishing - 0.025" depth, 0.007"/rev feed - 200 SFM
Drilling :	1/4" Dia hole - 0.004"/rev feed - 60 SFM 1/2" Dia hole - 0.007"/rev feed - 60 SFM 3/4" Dia hole - 0.010"/rev feed - 60 SFM
Reaming :	Feed - same as drilling - 100 SFM
Side and Slot Milling :	Roughing - 0.25" depth - 0.007"/tooth feed - 125SFM Finishing - 0.050" depth - 0.009"/tooth feed - 140SFM
These rates are for carbide tools, Type C-2 for roughing, drilling and reaming. Type C-3 for finishing.

NITRONIC is a registered tradename of Armco, Inc.

Material in this bulletin has been reprinted from Armco Bulletin No S-45, other Armco sources, and HPA data.