Heat Resistant Alloys

NAS 660

  • JISSUH 660
  • UNSS66286
  • DIN/EN
A-286 Alloy

A precipitation hardening stainless steel, NAS 660 (SUH 660, UNS S66286) maintains superior strength at high temperatures up to 700℃, surpassing austenitic stainless steels. With a higher nickel content than Type 304, NAS 660 also includes such elements as titanium and aluminum for hardening. Age hardening is used to precipitate γ' phase [Ni3 (Al, Ti)] making this an extraordinarily strong metal at high temperatures. Nippon Yakin supplies this product in plate, sheet, and strip forms.

Products & Materials

NAS 660ProductsPDF(314KB)

Chemical Composition 25Ni-15Cr-1Mo-2Ti-0.3V-0.2Al
Product shape
Weldability Spot, TIG, MIG and shield metal arc welding can be used on thin NAS 660 sheets under similar conditions to austenitic stainless steels.
Heat Treatment NAS 660 is a precipitation hardening alloy. Its strength is increased through aging after solution heat treatment. Two stages of heat treatment are generally carried out, as follows:
・Solution heat treatment: 980℃; oil or water cooling
・Age hardening: 720℃ × 16hr; air cooling
After solution heat treatment, either oil or water cooling is required, though air cooling is better for thinner metal. Note that it is important to use a suitable temperature and holding time for aging to obtain the target strength.
Machinability Compared to standard austenitic stainless steels, NAS 660 has somewhat superior machining properties. Although a high-speed steel tool can be used, we recommend the use of a sintered carbide tool, and suggest combining a slower feed rate with a greater cutting depth.
Applications NAS 660 is an excellent choice when high-temperature strength is required such as jet engines, gas turbines and turbo charger components.