NAS 354N； Corrosion Resistant Super Stainless Steel
Characteristics of NAS354N
A highly corrosion resistant austenitic stainless steel, NAS 354N (UNS N08354, ASME Code Case 2585) provides pitting corrosion resistance and crevice corrosion resistance on par with a nickel-based corrosion resistant alloy, a step above conventional stainless steels.
Chemical Composition (Examples)
(%)
| Grades | C | Si | Mn | Ni | Cr | Mo | N |
| NAS 354N | 0.01 | 0.10 | 0.10 | 35.5 | 23.3 | 7.5 | 0.22 |
| NAS 254N(SUS 836L) | 0.01 | 0.10 | 0.20 | 25.5 | 22.9 | 5.5 | 0.20 |
| NAS 64(SUS 329J4L) | 0.01 | 0.70 | 0.70 | 6.3 | 25.0 | 3.3 | 0.10 |
Physical Properties
| Properties | NAS354N | NAS254N (SUS 836L) |
NAS64 (SUS 329J4L) |
|
| Density (X103) | G/cm2 | 8.16 | 8.06 | 7.80 |
| Specific resistivity | μΩ･cm | 102.6 | 93.1 | 88.7 |
| Thermal conductivity | W/(m･K) | 9.8 | 10.9 | 12.6 |
| Specific heat | J/kg･K | 419 | 460 | 460 |
| Coefficient of thermal expansion 10-6/℃ | 30〜200℃ | 14.13 | 14.86 | 10.46 |
| 30〜300℃ | 14.69 | 15.50 | 11.39 | |
| 30〜400℃ | 15.20 | 15.96 | 12.24 | |
| Young's modulus (x104) at 25℃ | MPa | 19.3 | 18.8 | 19.6 |
| Melting point | ℃ | 1,362〜1,391 | 1,330〜1,390 | 1,420〜1,462 |
| Ferromagnetism | None | None | Yes |
Mechanical Properties
Mechanical Properties at Room Temperature
| Grades | 0.2% Proof stress （MPa） |
Tensile strength （MPa） |
Elongation （%） |
Hardness | |
| (Hv) | (HRB) | ||||
| NAS 354N | 393 | 795 | 51.8 | 188 | 89.0 |
| NAS 254N(SUS 836L) | 363 | 745 | 48.7 | 184 | 88.0 |
| NAS 64(SUS 329J4L) | 647 | 853 | 23.0 | 258 | 100.7 |
High Temperature Strength
High temperature tensile test result
Corrosion Resistance
Pitting corrosion resistance
Critical pitting corrosion resistance (10%FeCl3・6H2O+1/20N HCl水溶液)
Crevice corrosion resistance
Critical crevice corrosion temperatur (10%FeCl3・6H2O+1/20N HClsolution, crevice formed by teflon)
Stress corrosion cracking resistance
Stress corrosion cracking test result
(in boiling MgCl2 environment, for 300hrs., U-bend specimen, 2 mm thick, #500 Finish)
| MgCl2Solution | Occurrence of SCC | |||
| Concentration(％) | Temperature (℃) | NAS354N | NAS254N(SUS 836L) | NAS64(SUS 329J4L) |
| 20 | 108 | No SCC | No SCC | No SCC |
| 25 | 110 | No SCC | No SCC | No SCC |
| 30 | 115 | No SCC | No SCC | SCC |
| 35 | 126 | No SCC | No SCC | SCC |
| 42 | 142 | No SCC | SCC | SCC |
Acid Resistance, Alkaline Resistance
Evaluation of Acid and Alkaline Resistance
（Dipping test for 2mm thickness #400finish specimens）
| Test condition | Corrosion rate(g/m2・h) | |||||
| Acid | Concentration(％) | Temperature(℃) | Duration(h) | NAS354N | NAS254N(SUS 836L) | NAS64(SUS 329J4L) |
| H2SO4 | 5.0 | boil | 6 | 0.34,0.37 | 0.52, 0.57 | 0.57, 0.68 |
| HCl | 0.5 | boil | 6 | 0, 0.03 | 0, 0.03 | 0.02 |
| 2 | boil | 6 | 20.9, 29.3 | 37.7, 37.8 | - | |
| HCOOH | 60 | boil | 72 | 0.12, 0.13 | 0.21, 0.21 | 0.24. 0.30 |
| H3PO4 | 50 | boil | 24 | 0.09, 0.11 | 0.05, 0.06 | 0.09 |
| NaOH | 70 | 100 | 24 | 0, 0 | 0, 0 | - |
Weldability
NAS 354N alloy can be shield metal arc welded, TIG welded and plasma welded much as any standard austenitic stainless steel. We recommend using HastelloyR C-type welding consumables with this product. (Hastelloy is a registered trade mark of Haynes International, Inc)
Workability
Although NAS 354N can be hot- and cold-worked much like standard austenitic stainless steels such as Type 304 and Type 316, the high strength of the alloy must be kept in mind when doing so.
Machinability
As with any stainless steel endowed with a high nickel content, machining NAS 354N is more challenging than standard austenitic stainless steels, though NAS 354N is more easily handled than other nickel-based alloys. We recommend the use of cemented carbide tool, and suggest combining a slower feed rate with a greater cutting depth.
Heat treatment
As NAS 354N is an austenitic stainless steel, the same sort of heat treatment may be used. We suggest water-cooled solution treatment in a range between 1125 and 1175℃.
Application
・High concentration of chloride ion(≧104ppm) environment; Flue gas desulphurization equipment, Salt manufacturing Plant, Seawater desalination plant
・Oxidizing environment with chloride ion; bleaching equipment in pulp and paper mills
・Environments containing high chloride ion: plastic manufacturing equipment, chemical reactor vessels and tubing of chemicals manufacturing process where SCC is concerned.
