Nippon Yakin Kogyo NASNW22 Corrosion Resistant Alloys

Manufacturer: Nippon Yakin Kogyo Co., Ltd
Model : NASNW22

Chemical Composition57Ni 21Cr 14Mo 3W 4Fe
Product shapeNippon Yakin Kogyo NASNW22 Corrosion Resistant AlloysCoilNippon Yakin Kogyo NASNW22 Corrosion Resistant AlloysSheetNippon Yakin Kogyo NASNW22 Corrosion Resistant AlloysPlate
WorkabilityHigh-temperature strength is higher than Type 304, requiring care when hot working. Cold workability similar to standard austenitic stainless steels like Type 304, 316, etc. When performing cold work, consider the high strength of the material.
WeldabilityOrdinary welding methods can be used with stainless steels. Matching welding consumables should be used. You do not need to perform post-weld heat treatment.
Heat TreatmentSolution annealing at 1150–1170°C, followed by quenching in water or rapid cooling.
PicklingNitric acid and hydrofluoric acid used in pickling.Descaling is more challenging compared to Type 304, so it’s essential to proactively implement stronger techniques such as alkaline immersion before pickling or shot blasting to improve efficiency.Alkaline immersion before pickling and shot blasting are effective.
ApplicationsChemical plants, Pharmaceutical plants, Environment-related equipment, Heat exchangers.
Chemical Composition57Ni 21Cr 14Mo 3W 4Fe

Grade/Standard

Nippon Yakin GradeJIS G 4902ASTM B575DIN 17744/17750
NASNW22NW6022UNS N060222.4602

Chemical Composition

CSiMnPSNiCrMoFeCoWV
Specification (NW6022)≤0.015≤0.08≤0.50≤0.020≤0.020Bal.20.00-22.5012.50-14.502.00-6.00≤2.502.50-3.50≤0.35
Specification (UNS N06022)≤0.015≤0.08≤0.50≤0.02≤0.02Bal.20.00-22.5012.50-14.502.00-6.00≤2.52.5-3.5≤0.35

Physical Properties

Density [g/cm³]8.70
Specific heat [J/kg•K]414
Electrical resistivity [μΩ•cm]114.0
Thermal conductivity [W/m•K]10.0
Average coefficient of thermal expansion [10⁻⁶/°C]20–100°C 11.5
20–200°C 12.7
20–300°C 13.0
20–400°C 13.5
20–500°C 13.8
Young’s modulus [MPa]20.4 × 10⁴
MagnetismNone
Melting range [°C]1325–1372

Mechanical Properties

0.2% proof stress [MPa]Tensile strength [MPa]Elongation [%]Hardness [HRBW]
Specification (NW6022)≥310≥690≥45
Specification (UNS N06022)≥310≥690≥45
Hot-rolled plate (12mm)3677447388
Cold-rolled sheet (3mm)3837825786

Corrosion Resistance

Pitting Corrosion Resistance

AlloyASTM G48 Method AASTM G48 Method C Critical pitting corrosion temperature CPT (°C)
NAS185N70
NAS254N80
NASNW22>103

Test conditions: ASTM G48 Method A (○: No pitting corrosion, X: Pitting corrosion)
– Test solution: 6% FeCl₃
– Test temperature: 22°C, 50°C (Recommended temperature in this test)
– Test time: 72h

Crevice Corrosion Resistance

AlloyASTM G48 Method D Critical crevice corrosion temperature CCT (°C)
NAS185N40
NAS254N45
NASNW22>103

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

Intergranular Corrosion Resistance

Nippon Yakin Kogyo NASNW22 Corrosion Resistant Alloys

Test conditions: ASTM G28 Method A
Test time: 24h
Boiling 50% H₂SO₄ – Fe (SO₄) solution

Stress Corrosion Cracking Resistance

AlloyMgCl₂ concentration (boiling point °C in brackets)45% (153°C)38% (142°C)35% (136°C)30% (123°C)25% (119°C)20% (110°C)
NAS185Nxxxx
NAS254N
NASNW22

Test conditions:
– Immersion in boiling MgCl₂ solution
– Test time: 300h
○: No stress corrosion cracking, x: Stress corrosion cracking
They use a U-bend test specimen.

Acid Resistance

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

Alloy5%10%20%40%60%80%
NAS185N0.020.041.322.893.024.78
NAS254N0.020.050.062.112.767.76
NASNW220.010.020.040.070.34

Test time: 24h

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

Alloy0.1%1%2%3%5%
NAS185N0.010.024.297.21
NAS254N0.010.020.022.967.74
NASNW220.020.030.04

Test time: 24h

Reference

AlloyJISUNS No.Chemical Composition
NAS185NSUS312LS3125420Cr-18Ni-6Mo-0.8Cu-0.2N
NAS254NSUS836LS3260323Cr-25Ni-5.5Mo-0.2N
NASNW22NW6022N0602257Ni-21Cr-14Mo-3W-4Fe

Workability

Because NASNW22 has much higher high-temperature strength than Type 304, operators must take extra care when hot working. NASNW22’s cold workability is similar to standard austenitic stainless steels like Type 304 and Type 316. However, operators must account for its high-strength properties during cold working.

Weldability

In welding, it is possible to apply ordinary welding methods in the same manner as with stainless steels. Matching composition welding consumables should be used. Post-weld heat treatment is not required.

Heat Treatment

Solution annealing of NASNW22 is normally performed at the temperature range from 1150 to 1170°C followed by being quenched in water or rapidly cooled by other means.

Pickling

A mixture of nitric acid and fluoric acid is used in pickling. However, because descaling is somewhat difficult in comparison with Type 304, alkali immersion before acid pickling, and if possible, shot blasting are extremely effective.

Applications

Chemical plants, Pharmaceutical plants, Environment-related equipment, Heat exchangers.

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