NAS 224N (UNS S32050)

NAS High Corrosion Resistant Super Stainless SteelNAS 224N (UNS S32050) is a high corrosion resistant austenitic stainless steel with a high nickel, high chromium,high molybdenum alloy design, and provides excellent corrosion resistance in severe corrosion environments suchas high temperature seawater. Depending on the environment, this stainless steel offers high economy combinedwith corrosion resistance comparable to that of Nickel alloy and pure titanium. Nippon Yakin supplies NAS 224N inplate, sheet and strip forms.

Steel Grade/StandardNASJISASTM A240

NAS 224N—UNS S32050

Chemical Composition[wt %]

Specification(UNS S32050)

CSi

MnPS

NiCrMo

CuN

0.030

1.00

1.50

0.035

0.020

20.0~
23.0

22.0~
24.0

6.0~
6.8

0.40

0.21~
0.32

Physical Properties
Density[g/cm3]

8.04

Specific heat

[J/kg . K]

455

Electrical resistivity[μΩ . cm]

95.2

Thermal conductivity[W/m . K]

11.5

Average coefficient of thermal expansion[10–6/°C]

Young’s modulus[MPa]

Magnetism
Melting range

20~100°C

15.0

20~200°C

15.4

20~300°C

15.7

20~400°C

16.121.6 × 104
None

[°C]

1350~1400

NAS 224N (UNS S32050)

Mechanical Properties
Mechanical Properties at Room Temperature
0.2% proof stress Tensile strength

Elongation

Elongation

675

40250

800

46193 (Hv)

[MPa]

[MPa]

Specification: Cold-rolled sheet (UNS S32050)

330

Example401

Cold-rolled sheet

Corrosion Resistance

0.7mmt[%][HB]

Due to its high contents of chromium and molybdenum, NAS 224N has extremely
high pitting resistance and crevice corrosion resistance in high concentration chloride environments. As a high Ni stainless steel, it also possesses excellent stresscorrosion cracking (SCC) resistance.

Pitting Corrosion ResistanceAlloy

ASTM G48 Method A

ASTM G48 Method C22°C50°C

Critical pitting corrosion temperature CPT (°C)

NAS 255○×50

NAS 329J3L○×50

NAS 64○○55○○NAS 224N
Test conditions

ASTM G48 Method A (○: No pitting corrosion, ×: Pitting corrosion)• Test solution: 6%FeCl3• Test temperature: 22°C, 50°C (Recommended temperature in this test)• Test time: 72h95
ASTM G48 Method C• Test solution: 6%FeCl3 + 1%HCl• Test time: 72hCrevice Corrosion ResistanceAlloy

ASTM G48 Method D
Critical crevice corrosion temperature CCT (°C)

NAS 255

10NAS 329J3L

25NAS 64

30NAS 224N
Test conditions

45
ASTM G48 Method D• Test solution: 6%FeCl3 + 1%HCl• Test time: 72h

NAS 224N (UNS S32050)

Stress Corrosion Cracking Resistance
MgCl2 concentration (boiling point (°C) are in brackets)
Alloy

45%

42%

40%

38%

35%

30%

25%

20%

(155°C)(143°C)(138°C)(134°C)(126°C)(115°C)(110°C)(108°C)NAS 255

××××

○○○

○

NAS 329J3L

××××××○○NAS 64××××××○○××××○○○○NAS 224N
Test conditions• Immersion in boiling MgCl2 solution• Test time: 300h
• U-bend test specimen is used.

○: No stress corrosion cracking
×: Stress corrosion cracking(Reference)

Nippon YakinJISUNS No.

Chemical composition

NAS 255

SUS 890L

N0890420Cr-24Ni-4.3Mo-1.5Cu

NAS 329J3L

SUS 329J3L

S3220522Cr-5.3Ni-3.2Mo-0.16N

NAS 64

SUS 329J4L

S3250625Cr-6.5Ni-3.3Mo-0.17N

NAS 224N—

S3205023Cr-22Ni-6Mo-0.25N

NAS 224N (UNS S32050)

Workability

Cold and hot workability of NAS 224N is basically the same as that of Type 304,
316, and other standard austenitic stainless steels. However, the fact that this is ahigh strength material must be considered in both cold and hot working.

Weldability

Welding is possible by shielded metal arc welding, TIG welding, and plasma
welding, in the same manner as with standard austenitic stainless steels. Alloy
276 welding consumables should be used. Preheating and post-heating are notrequired.

Machinability

As a distinctive feature of high Ni stainless steels, machining is difficult in comparison with standard austenitic stainless steels, but is easier than with Ni-based
alloys. Cemented carbide cutting tools should be used if possible. Use of a slower
feed rate in combination with greater cutting depth is recommended.

Heat Treatment

Solution annealing of NAS 224N should be performed at 1150°C and higher followed by being quenched in water or rapidly cooled by other means. (Conditions
provided in ASTM A480/A480M)

Pickling

A mixed acid of nitric acid and hydrofluoric acid is used in pickling. Descaling issomewhat more difficult than with Type 304, corresponding to the higher corrosion
resistance of NAS 224N. Before pickling, brief immersion in an alkaline solution,and if possible, shot blasting, is extremely effective for improving descaling.

Applications• Seawater environments: Seawater desalination systems, seawater heat exchangers, condenser tubes• High concentration chloride ion environments: Pulp and paper plant, various
types of bleaching systems

For more information, please contact:
Nippon Yakin Kogyo Co., Ltd.
Material Solutions Sales Department
San-Ei Bldg., 5-8, 1-chome Kyobashi, Chuo-ku,
Tokyo 104-8365 Japan
TEL: +81-3-3273-4649 FAX: +81-3-3273-4642
E-Mail: inquiry@nyk.jp
URL: http://www.nyk.co.jp/en/

Note regarding the handling of property data:
The technical information contained in this product guide is representativevalues obtained in property tests and other items used to explain the performance of the product. With the exception of items specifically mentioned
as provisions of a “Standard,” the contents do not represent guaranteed
upper limit or lower limit values. The respective data given on this technicalinformation are typical examples and may be different in some cases fromthe data obtained from the actual product. No responsibility shall, therefore,
be assumed for damages arising from using the technical information data.
This information is also subject to change in the future without notice. To
obtain the most recent information, please contact Nippon Yakin.

2016.6.10