NAS NW22G@High Nickel Corrosion Resistant Alloy
Characteristics of NAS NW22
NAS NW22 is a Ni-Cr-Mo alloy with excellent pitting, crevice corrosion, and stress corrosion cracking resistance in both oxidizing and reducing atmospheres. Based on these features, NAS NW22 is widely used in materials under severe environments such as flue gas desulphurization apparatus, pulp and paper industry, and waste treatment plants.
Chemical Composition
(%)
@ | C | Si | Mn | P | S | Ni | Cr | Mo | Fe | Co | W | V |
NAS NW22 | 0.004 | 0.04 | 0.31 | 0.008 | 0.0005 | Bal | 21.2 | 13.9 | 4.5 | 0.01 | 3.0 | 0.01 |
Corresponding Standard
ASTM B575 / UNS N06022
ASME SB575 / UNS N06022
JIS H4551 / NW6022
Mechanical Properties
@ | @ | 0.2% Proof stress iMPaj |
Tensile strength iMPaj |
Elongation ij |
Hardness iHRBj |
NAS NW22 | Hot rolled material@(12mm thick) | 367 | 744 | 73 | 84 |
Hot rolled material (8mm thick) | 365 | 752 | 69 | 84 | |
Hot rolled material (3mm thick) | 383 | 782 | 57 | 86 |
Physical Properties
@ | Temperature() | Properties |
Density | RT | 8.69 g/cm3 |
Melting point | @@ | 1325`1372 |
Electrical resistivity | RT | 1.14 ΚΆEm |
Coefficient of thermal expansion | 20`100 20`200 20`300 20`400 20`500 20`600 20`700 20`800 20`900 20`1000 |
12.4 Κm/mE 12.4 Κm/mE 12.6 Κm/mE 13.1 Κm/mE 13.7 Κm/mE 14.2 Κm/mE 14.8 Κm/mE 15.3 Κm/mE 15.9 Κm/mE 16.4 Κm/mE |
Young’ modulus | RT | 204 GPa |
Modulus in torsion | RT | 78.8 GPa |
Thermal properties
Temperature () |
Specific heat (J/kg₯) |
Thermal conductivity (W/₯) |
Thermal diffusivity (m2/s) |
25 | 440 | 10.6 | 2.8~10-6 |
100 | 469 | 12.5 | 3.1~10-6 |
200 | 487 | 14.7 | 3.1~10-6 |
300 | 502 | 16.5 | 3.8~10-6 |
400 | 507 | 18.0 | 4.1~10-6 |
500 | 522 | 20.7 | 4.6~10-6 |
600 | 549 | 22.7 | 4.8~10-6 |
Workability
Figure 1 shows the effect of cold reduction on hardness.
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Heat Treatment
The solution treatment temperature of NAS NW22 ranges from 1150 to 1170. Rapid cooling of the alloy is necessary after heating.
Corrosion Resistance
Pitting Resistance
Grades | Critical pitting temperature [CPT] () | |
6%FeCl3 + 1%HCl solution (ASTM G48 Method C) |
Green death solution | |
NASNW22 | 120 | 120 |
NASNW276 | 120 | 120 |
NAS254N | 80 | 80 |
NAS329J3L | 50 | 45 |
SUS316L | 10 | 25 |
Crevice corrosion resistance
Grades | Critical crevice corrosion temperature [CCT] () | |
6%FeCl3 + 1%HCl solution (ASTM G48 Method D) |
Green death solution | |
NASNW22 | 100 | 110 |
NASNW276 | 100 | 110 |
NAS254N | 40 | 15 |
NAS329J3L | 25 | 30 |
SUS316L | 0 | 0 |
Test condition@@ASTM G48 Method C FTest duration of 72 hours
@@@@@@@@@@@AASTM G48 Method D FTest duration of 72 hours with multi crevices
@@@@@@@@@@@BGreen death solution immersion testFTest duration of 24 hours
@@@@@@@@@@@@@@@@@@@@@@@@@Test solutionF 7%H2SO4+3%HCl+1%FeCl3+1%CuCl2
@@@@@@@@@@@@@@@@@@@@@@@@@Multi crevice method was applied to crevice corrosion test.
Intergranular corrosion resistance
@@@@@@@@@@
@Test conditionFASTM G28 Method A
@24 hours of test duration in boiling 50%H2SO4]Fe2(SO4)3solution
Stress Corrosion Cracking Resistance
Grades | MgCl2Concentration (Boiling temperature) | |||||
20% (108) |
25% (110) |
30% (115) |
35% (126) |
38% (134) |
42% (142) |
|
NASNW22 | | | | | | |
NASNW276 | | | | | | |
NAS254N | | | | | | ~ |
NAS329J3L | | | ~ | ~ | ~ | ~ |
SUS316L | | ~ | ~ | ~ | ~ | ~ |
@@@@@@@@@@@@@@@@@@@@@@: no SCC, ×: SCC
@
Test condition: U bend specimen immersed in boiling MgCl2 solution for 300 hours.
Acid corrosion resistance
Grades | Temperature () |
Concentration () |
Corrosion rate (g/m2Ehr) | ||||
NASNW22 | NASNW276 | NAS254N | NAS329J3L | SUS316L | |||
H2SO4 | 80 | 5 | 0.01 | 0.02 | 0.02 | 0.00 | 1.10 |
10 | 0.02 | 0.03 | 0.02 | 0.14 | 2.92 | ||
20 | 0.02 | 0.04 | 1.16 | 3.33 | 20.1 | ||
40 | 0.04 | 0.06 | 1.78 | 250.5 | 291.3 | ||
60 | 0.47 | 0.08 | 1.86 | 263.1 | 72.0 | ||
80 | 0.34 | 0.03 | 2.82 | 90.4 | 11.1 | ||
Boiling | 5 | 0.14 | 0.10 | 1.43 | 0.61 | 5.45 | |
10 | 0.25 | 0.16 | 2.49 | 3.30 | 18.0 | ||
20 | 0.72 | 0.33 | 6.18 | 76.2 | 108.7 | ||
40 | 3.24 | 1.44 | 21.0 | 271.7 | 297.8 | ||
HCl | 80 | 0.1 | 0.00 | 0.00 | 0.00 | 0.00 | 0.01 |
1.0 | 0.00 | 0.02 | 0.00 | 0.01 | 2.45 | ||
2.0 | 0.01 | 0.03 | 3.15 | 19.0 | 6.66 | ||
3.0 | 0.03 | 0.33 | 12.8 | 51.5 | 13.6 | ||
Boiling | 0.1 | 0.00 | 0.00 | 0.00 | 0.00 | 0.01 | |
1.0 | 0.13 | 0.23 | 0.13 | 4.82 | 6.32 | ||
2.0 | 1.32 | 0.91 | 27.8 | 56.7 | 33.6 | ||
3.0 | 3.63 | 1.64 | 54.2 | 145.2 | 69.1 |
Test condition: Test duration of 24 hours
@