NAS600；Nickel Base Alloy
Characteristics of NAS600
A nickel-base alloy containing 14 to 17 percent chromium, NAS 600 (NCF 600, UNS N06600), comparable to Alloy 600, provides the maximum level of resistance against high temperature oxidation. It is also commonly used as a corrosion resistant alloy for its durability in the presence of a range of acids and alkalis.
Chemical Composition
(%)
| C | Si | Mn | P | S | Ni | Cr | Co | Fe | |
| NAS 600 | ≦0.15 | ≦0.50 | ≦1.00 | ≦0.030 | ≦0.015 | ≧72.00 | 14.00 ～17.00 |
≦1.00 | 6.00 ～10.00 |
Designation/Standard
ASTM(ASME):UNSN06600,JIS:NCF600
Physical Properties
| Density g/cm3 | 8.43 |
| Specific heat J/(kg･k) 25～100℃ | 444 |
| Specific electric resistance μΩ-cm | 103 |
| Thermal Conductivity W/(m･k) 100℃ 200℃ 400℃ 600℃ 800℃ |
15 17.2 18.8 20.9 22.6 |
| Coefficient of thermal expansion 10-6/℃ 0～93℃ 0～316℃ 0～538℃ 0～760℃ 0～982℃ |
13.3 14.2 15.1 16.0 16.7 |
| Curie point ℃ | -124 |
| Young's Modulus MPa | 213,785 |
| Modulus of Rigidity MPa | 75,511 |
| Poisson ratio | 0.29 |
| Melting point ℃ | 1371～1427 |
| Magnetic permeability μ(at 21℃, 200 oersted) | 1.006 |
Mechanical Properties
Mechanical properties of NAS 600 are as follows;
Mechanical properties at room temperature
| Heat Treatment | 0.2% Proof stress (MPa) |
Tensile strength (MPa) |
Elongation (％) |
Hardness (HV) |
| Solution treated | 206～314 | 549～686 | 35～55 | 140～170 |
| As rolled | 618～863 | 824～1030 | 2～15 | ≧260 |
Mechanical properties at high temperature
| Temperature (℃) |
0.2% Proof stress (MPa) |
Tensile strength (MPa) |
Elongation (％) |
| 20 | 252 | 624 | 47 |
| 427 | 203 | 610 | 49 |
| 538 | 196 | 580 | 47 |
| 649 | 182 | 448 | 39 |
| 760 | 117 | 189 | 46 |
| 982 | 27 | 52 | 118 |
Creep Rupture Strength
Creep rupture strength depending on temperature is as follows.
| Heat Treatment | Temperature (℃) |
Creep rupture strength (MPa) |
||
| 10hr | 100hr | 1,000hr | ||
| Solution heat treated | 732 | 137 | 93 | 64 |
| 871 | 56 | 36 | 25 | |
| 982 | 30 | 20 | 13 | Annealed | 538 | 511 | 345 | 234 |
| 649 | 234 | 158 | 100 | |
| 760 | 89 | 58 | 38 | |
| 871 | 52 | 33 | 21 | |
Heat Treatment
NAS 600 is not a precipitation hardening alloy. Therefore heat treatment does not lead to hardening over time.
Typical heat treatments are as follows:
･ Solution treatment 1050-1150℃ Air or water cooling
･ Annealing 800-1050℃ Air or water cooling
･ Stress relief annealing 550-760℃ Air or water cooling
Care should be taken at temperatures exceeding 1050℃ as there is a strong tendency for the crystal grains to become coarse. Also less sulfur containing fuel must be used while heating and degreasing before heating are necessary.
Machinability
As a high-nickel alloy, NAS 600 is not as machinable as an austenitic stainless steel. Although a high-speed steel tool can be used, we recommend the use of cemented carbide tools, and suggest combining a slower feed rate with a greater cutting depth.
The recommended lathe feed speeds are as follows:
･ High-speed steel tool: 1050-1350 mm/min
･ Cemented carbide tool 3000-5250 mm/min
After machine work, the lubricant should be completely removed before welding or heat treating.
Workability
Hot working is relatively easy with NAS 600.Although heating between 1150 and 1180℃, hot working between 1000 and 1180℃ and light working as low as 850℃ are possible, the range between 650 and 850℃ should be avoided as cracking may occur. Low sulfur containing fuel should be used for heating materials.
The cold workability is easier than austenitic stainless steels, similar to Ni-Cu Alloy 400.
Characteristics
The composition of NAS 600 provides resistance protection in a remarkably large number of corrosive environments. The addition of chromium content provides superior corrosion resistance in acidic environments over pure nickel. Furthermore, the high nickel content maintains the corrosion resistance in a reducing state and exhibits superior corrosion resistance to alkaline solutions. Another feature of this product is the high level of resistance against stress corrosion cracking.
Exhibiting particularly strong heat resistance at high temperatures, NAS 600 can be used in air oxidizing as well as other environments continuously for long periods of time. Because is has excellent resistance to nitrogen, hydrogen and carburization, NAS 600 can be used in heat treatment furnaces. Care is needed with wet chlorine and bromide, however, as they will cause damage. The maximum temperatures that NAS 600 may be used in different environments are as follows:
･ Long-term continuous use in air oxidizing environment: 1100℃
･ Reducing environment of H2 or CO not containing sulfur: 1150℃
･ Oxidizing sulfur environment (in air containing sulfurous acid): 815℃
･ Reducing environment containing hydrogen sulfide: 535℃
･ Hydrogen chloride: 540℃
･ Chlorine gas: 510℃
Application
Nuclear power plants, heat exchangers, industrial chemical evaporators, industrial acid and alkali equipment, jet engine parts, heat treatment furnace parts, afterburner parts and other components used in high temperatures.
