Nippon Yakin Kogyo NAS335X Corrosion Resistant AlloysKouei Japan Trading

Manufacturer: Nippon Yakin Kogyo Co., Ltd
Model: NAS335X

Stainless steel alloys like JIS-UNS N08020 DIN/EN-NAS335X offer exceptional corrosion resistance to sulfuric acid, making them ideal for harsh chemical environments. These alloys perform well in high-concentration sulfuric acid and elevated temperatures, providing durability and protection against intergranular corrosion and stress corrosion cracking. They ensure long-lasting efficiency for industries facing aggressive chemical exposure.

Chemical Composition	20Cr-33Ni-2.5Mo-3Cu-0.4Nb
Product Shape	Coil	Sheet	Plate
Workability	Cold and hot workability are approximately equal to those of Type 304, 316, and other standard austenitic stainless steels.
Weldability	TIG welding, MIG welding, and shielded metal arc welding apply in the same manner as with standard austenitic stainless steels.It is recommended to use ER320 or ER320LR welding electrodes..However, reduce welding heat input as far as possible for Nb-added stainless steel.
Machinability	Machinability is similar to that of standard austenitic stainless steels. A machinist should use a high-speed steel tool or an ultrahard tool. Additionally, it is recommended to adopt a slower feed rate and a deeper cutting depth
Heat Treatment	Stabilizing heat treatment should be performed at a temperature range from 925°C to 1010°C, followed by quenching in water or rapid cooling by other means. (Conditions provided in ASTM A480/A480M).
Pickling	Pickling is performed under the same conditions as with Type 304, using a mixture of nitric acid and hydrofluoric acid.
Applications	Chemical plants, heat exchangers, sulfuric acid-related equipment.

Steel Grade/Standard

Nippon Yakin Grade	JIS G 4902	ASTM A240/B463	EN
NAS335X	NCF020	UNS N08020	—

Chemical Composition

Specification	C	Si	Mn	P	S	Ni	Cr	Mo	Cu	Nb
NCF020	≤0.07	≤1.00	≤2.00	≤0.045	≤0.035	32.00-38.00	19.00-21.00	2.00-3.00	3.00-4.00	8xC-1.00
ASTM A240	≤0.07	≤1.00	≤2.00	≤0.045	≤0.035	32.00-38.00	19.00-21.00	2.00-3.00	3.00-4.00	8xC-1.00
ASTM B463	≤0.07	≤1.00	≤2.00	≤0.045	≤0.035	32.00-38.00	19.00-21.00	2.00-3.00	3.00-4.00	8xC-1.00

Physical Properties

Density [g/cm³]	8.08
Specific heat [J/kg·K]	470
Electrical resistivity [µΩ·cm]	105
Thermal conductivity [W/m·K]	11.4
Average coefficient of thermal expansion [10⁻⁶/°C]	10–100°C: 14.6 20–200°C: 15.9 20–300°C: 15.8 20–400°C: 16.0
Young’s modulus [MPa]	18.9 x 10³
Magnetism	None
Melting range [°C]	1340–1389

Mechanical Properties

Mechanical Properties at Room Temperature

	0.2% proof stress [MPa]	Tensile strength [MPa]	Elongation [%]	Hardness [HBW]
Specification (NCF020)	≥240	≥550	≥30	≥217
Specification (ASTM A240)	≥240	≥550	≥30	≥217
Cold-rolled sheet 2.0mm	431	698	38	176
Hot-rolled plate 6.5mm	359	686	40	137
Hot-rolled plate 50mm	315	581	42	156

Corrosion Resistance

NAS335X contains high levels of Ni, Mo, and Cu, which provide it with excellent resistance to sulfuric acid. Furthermore, as a low carbon, Nb-added material, it also demonstrates outstanding intergranular corrosion resistance.Its combination of resistance to sulfuric acid and intergranular corrosion makes NAS335X an ideal material for challenging environments.

Pitting Corrosion Resistance

Alloy	ASTM G48 Method A		ASTM G48 Method C Critical Pitting Corrosion Temperature CPT (°C)
Alloy	22°C	50°C
SUS316L	✖	✖	—
NAS64	◯	◯	55
NAS254N	◯	◯	80
NAS335X	◯	◯	85

Test Conditions
ASTM G48 Method A: No Pitting Corrosion.
– Test Solution: 6% FeCl₃, 72h
ASTM G48 Method C: 6% FeCl₃ + 1% HCl, 72h

Crevice Corrosion Resistance

Alloy	ASTM G48 Method D Critical Crevice Corrosion Temperature CCT (°C)
SUS316L	<10
NAS64	30
NAS254N	45
NAS335X	55

Test Conditions
ASTM G48 Method D: Critical crevice corrosion temperature test.
– Test Solution: 6% FeCl₃ + 1% HCl, 72h

Acid Resistance

Alloy	Corrosion rate in sulfuric acid at 80°C (mm/y)
Alloy	5%	10%	20%	40%	60%	80%
SUS316L	1.67	4.69	7.191	24.90	70.45	33.74
NAS64	<0.01	0.02	1.07	19.19	1054	60.72
NAS254N	0.02	0.05	1.2	2.16	7.76	—
NAS335X	<0.01	0.02	0.31	0.12	0.09	2.15

Test time: 24h

Alloy	Corrosion rate in boiling sulfuric acid (mm/y)
Alloy	5%	10%	20%	40%
SUS316L	8.19	24.61	17.89	3129
NAS64	0.35	1.65	17.68	4829
NAS254N	1.17	3.30	7.90	24.65
NAS335X	0.44	0.68	0.52	2.64

Test time: 24h

(Reference)

Alloy	JIS	UNS No.	Chemical Composition
SUS316L	SUS316L	S31603	17Cr-12Ni-2Mo
NAS64	SUS329J4L	S32605	25Cr-6.5Ni-3.3Mo-0.17N
NAS254N	SUS836L	S32053	23Cr-25Ni-5.5Mo-0.2N
NAS335X	NCF020	N08020	20Cr-33Ni-2.5Mo-3Cu-0.4Nb

Workability

NAS335X offers the same hot and cold workability as standard austenitic stainless steels. Moreover, you can easily work with NAS335X under both hot and cold conditions, and at the same time maintain its excellent formability in various environments.

Weldability

Moreover, you can easily work with NAS335X under both hot and cold conditions, and at the same time maintain its excellent formability in various environments. To achieve optimal welding performance, use ER320 or ER320LR welding electrodes, ensuring the best results for welding NAS335X.

Machinability

NAS335X offers machinability similar to standard austenitic stainless steels. Moreover, for better machinability, using a high-speed steel tool or an ultrahard tool is recommended. Additionally, applying a slower feed rate and a deeper cutting depth ensures optimal results during machining.

Heat Treatment

To perform the stabilizing heat treatment of NAS335X, heat it within the temperature range of 925°C to 1010°C. After heating, quench it in water or rapidly cool it by other means, as outlined in ASTM A480/A480M..

Pickling

Perform pickling under the same conditions as for Type 304 stainless steel. Specifically, use a mixture of nitric acid and hydrofluoric acid for this process to ensure optimal results. By following these steps, you maintain the same effectiveness as when working with Type 304 stainless steel

Applications

NAS335X is commonly used in chemical plants, heat exchangers, and sulfuric acid-related equipment. Thus, its superior resistance to sulfuric acid makes it ideal for these industrial applications.

Nippon Yakin Kogyo Co., Ltd