Nippon Yakin Kogyo NAS254N Corrosion Resistant Alloys

Manufacturer: Nippon Yakin Kogyo Co., Ltd
Model: NAS254N

NAS254N (UNS S32053)
High Corrosion Resistant Super Stainless Steel

NAS254N (SUS836L, UNS S32053) is a high corrosion resistance austenitic stainless steel with a high nickel, high chromium, high molybdenum alloy design, and provides excellent corrosion resistance in severe corrosion environments such as high temperature seawater. Depending on the environment, this stainless steel offers high economy combined with corrosion resistance comparable to that of Nickel alloy and pure titanium. Nippon Yakin supplies this product in plate, sheet, and strip form.

Chemical Composition23Cr-25Ni-5.5Mo-0.2N
Product shape

Coil

Sheet

Plate

WorkabilityHot and cold workability similar to standard austenitic stainless steels like Type 304, 316; requires care due to high strength
WeldabilityVarious methods applicable; shielded metal arc welding, TIG welding, and plasma welding suitable. Alloy 276 consumables recommended.
MachinabilityMachining is difficult but easier than Ni-based alloys; use of ultra-hard tool and slow feed rate recommended
Heat TreatmentSolution annealing at 1080-1180°C, quenching in water or rapid cooling
PicklingMixture of nitric acid and hydrofluoric acid; material should be immersed in alkaline solution before pickling, shot blasting effective
ApplicationsFood manufacturing, Salt manufacturing, Pharmaceutical plants, Chemical plants, Marine structures, Heat exchangers

Steel Grade/Standard

Nippon Yakin GradeJIS G 4304/4305ASTM A240EN
NAS254NSUS836LUNS S32053

Chemical Composition

SpecificationCSiMnPSNiCrMoN
SUS836L≤0.030≤1.00≤2.00≤0.045≤0.03024.00 – 26.0019.00 – 24.005.00 – 7.00≤0.25
UNS S32053≤0.030≤1.00≤1.00≤0.030≤0.01024.00 – 26.0022.00 – 24.005.00 – 6.000.17 – 0.22

Physical Properties

Density [g/cm³]8.06
Specific heat [J/kg·K]457
Electrical resistivity [µΩ·cm]94.7
Thermal conductivity [W/m·K]11.9
Average coefficient of thermal expansion [10⁻⁶/°C]30-100°C: 14.6
30-200°C: 15.2
30-300°C: 15.5
30-400°C: 15.8
Young’s modulus [MPa]19.7 × 10⁴
MagnetismNone
Melting range [°C]1330 – 1390

Mechanical Properties

Mechanical Properties at Room Temperature

Specification0.2% proof stress [MPa]Tensile strength [MPa]Elongation [%]Hardness [HBW]Hardness [HRBW]Hardness [HV]
SUS836L≥275≥640≥40≤217≤96≤230
UNS S32053≥295≥640≥40≤217≤96
Cold-rolled sheet 2mm38576046
Hot-rolled plate 16mm33672556172
Corrosion Resistance

NAS254N is a high Cr, high Mo stainless steel which provides excellent pitting corrosion resistance and crevice corrosion resistance in high Cl environments. As a high Ni steel, it also offers excellent stress corrosion cracking resistance.

Pitting Corrosion Resistance

Alloy

ASTM G48 Method AASTM G48 Method CCritical pitting corrosion temperature CPT (°C)

22°C

50°C

NAS255

×

50

NAS329J3L×

50

NAS64

55

 

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: 72h

Crevice Corrosion Resistance

Alloy

ASTM G48 Method D

Critical crevice corrosion temperature CCT (°C)

NAS255

10
NAS329J3L

25

NAS64

30

NAS254N

45

 

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

Stress Corrosion Cracking Resistance

AlloyMgCl₂ concentration (boiling point °C are in brackets)
45% (155°C)42% (143°C)40% (138°C)38% (134°C)35% (126°C)30% (115°C)25% (110°C)20% (108°C)
NAS255××××
NAS329J3L×××××
NAS64××
NAS254N

Test conditions: Immersion in boiling MgCl₂ solution
They use a U-bend test specimen.
○: No stress corrosion cracking
×: Stress corrosion cracking

Acid Resistance

Corrosion rate in sulfuric acid at 80°C (mm/y)

Alloy5%10%20%40%60%80%
NAS255<0.01<0.010.782.950.485.01
NAS329J3L0.010.174.65365.9145.6106.4
NAS64<0.010.021.07191.9105460.72
NAS254N0.020.051.022.112.167.76

Test time: 24h

Corrosion rate in hydrochloric acid at 80°C (mm/y)

Alloy0.1%1%2%3%
NAS255<0.010.012.703.72
NAS329J3L0.020.0331.1060.62
NAS640.010.1212.9430.51
NAS254N0.010.020.019.14

Test time: 24h

Reference

AlloyJISUNS No.Chemical composition
NAS255SUS890LN0890420Cr-24Ni-4.3Mo-1.5Cu
NAS329J3LSUS329J3LS3220522Cr-5.3Ni-3.0Mo-0.16N
NAS64SUS329J4LS3260525Cr-6.5Ni-3.3Mo-0.17N
NAS254NSUS836LS3205323Cr-25Ni-5.5Mo-0.2N

Workability

The hot and cold workability of NAS254N is basically the same as that of standard austenitic stainless steels such as Type 304, Type 316, etc. The fact that this is a high-strength material requires consideration in both cold and hot working.

Weldability

Various welding methods are applicable in the same manner as with the standard austenitic stainless steels, including shielded metal arc welding, TIG welding, and plasma welding. Alloy 276 welding consumable should be used.

Machinability

As a feature of high Ni stainless steels, although machining is difficult in comparison with the standard austenitic stainless steels, it is easier than with Ni-based alloys. A ultrahard tool should be used in machining if at all possible. It is also advisable to use a slower feed rate and deeper cutting depth.

Heat Treatment

Solution annealing of NAS254N should be performed at the temperature range from 1130 to 1180°C followed by being quenched in water or rapidly cooled by other means. (Conditions provided in ASTM A480/A480M)

Pickling

A mixture of nitric acid and hydrofluoric acid is used in pickling. However, due to the high corrosion resistance of NAS254N, scale is somewhat difficult to remove in comparison with Type 304. Therefore, the material should be immersed in an alkaline solution before pickling or, if possible, shot blasting is extremely effective.

Applications

Food manufacturing plants, Salt manufacturing plants, Pharmaceutical plants, Chemical plants, Flue gas desulfurization plants, Marine structures, Marine equipment, related equipment, Heat exchangers, Various types of bleaching equipment.

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