特色製品

NAS NW22；　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
（MPa）		 Tensile strength
（MPa）		 Elongation
（％）		 Hardness
（HRB）
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 μΩ・m
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 μm/m・℃
12.4 μm/m・℃
12.6 μm/m・℃
13.1 μm/m・℃
13.7 μm/m・℃
14.2 μm/m・℃
14.8 μm/m・℃
15.3 μm/m・℃
15.9 μm/m・℃
16.4 μm/m・℃
Young’ modulus RT 204 GPa
Modulus in torsion RT 78.8 GPa

Thermal properties

Temperature
(℃)		 Specific heat
(J/kg･℃)		 Thermal conductivity
(W/ｍ･℃)		 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.

　　　　　　　　　　NAS NW22

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　①ASTM G48 Method C ：Test duration of 72 hours
　　　　　　　　　　　②ASTM G48 Method D ：Test duration of 72 hours with multi crevices
　　　　　　　　　　　③Green death solution immersion test：Test duration of 24 hours
　　　　　　　　　　　　　　　　　　　　　　　　　Test solution： 7%H2SO4+3%HCl+1%FeCl3+1%CuCl2
　　　　　　　　　　　　　　　　　　　　　　　　　Multi crevice method was applied to crevice corrosion test.

Intergranular corrosion resistance

　　　　　　　　　　NAS NW22

　Test condition：ASTM 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/m2・hr)
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

　

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