NAS STAINLESS STEEL STRIP MFG. CO., LTD. - NAS NW22；　High Nickel Corrosion Resistant Alloy

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.

(%)

	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

ASTM B575 / UNS N06022

ASME SB575 / UNS N06022

JIS H4551 / NW6022

		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

	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

Figure 1 shows the effect of cold reduction on hardness.

　　　　　　　　　　 NAS NW22

The solution treatment temperature of NAS NW22 ranges from 1150 to 1170℃. Rapid cooling of the alloy is necessary after heating.

Pitting Resistance

Grades	Critical pitting temperature [CPT] (℃)
Grades	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] (℃)
Grades	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)
Grades	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)
Grades	Temperature (℃)	Concentration (％)	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