Nimonic 81

Nimonic 81 is a wrought nickel alloy hardened by controlled additions of titanium and aluminum, and designed to provide enhanced resistance to high temperature corrosion coupled with good high temperature strength. It has excellent hot corrosion resistance due to its high chromium content.

 

Elevated temperature strength characteristics are similar to those of Nimonic alloy 80A. Melting, hot-working, cold-working and machining practices are also broadly similar to those for Nimonic alloy 80A.

 

Applications include components for gas turbines, piston engine exhaust valves, and heat-exchange plant subject to attack by deposits resulting from the combustion of impure fuels, particularly by alkali meta sulfates and chlorides.

Traditional machining methods that are used for iron-based alloys can be used for Nimonic 81. This alloy can be work-hardened during machining. Before cutting is performed, it is recommended that heavy duty machining equipment and tooling should be used so as to reduce chatter or work-hardening of the alloy. During high speed operations such as grinding, turning, or milling, water-base coolants are suitable. The use of heavy lubricants while drilling, tapping, broaching or boring is recommended.

Nimonic 81 has good ductility and can be easily formed using all the conventional methods. This alloy is stronger than regular steel; hence it requires a more powerful equipment to complete the forming process. It is recommended that heavy-duty lubricants should be used while cold forming. At the end of this process, all traces of lubricant has to be cleaned off to prevent embrittlement.

Nimonic 81 can be welded using the traditional welding methods. Some of the commonly used methods are shielded metal-arc welding, gas metal-arc welding, submerged-arc welding, and gas-tungsten arc welding. It is recommended that matching alloy filler metal should be used and that the weld beads should be slightly convex. Before the welding process begins, the surface to be welded should be cleaned and should be free from oil, paint or crayon stains.

Nimonic 81 has to be solution annealed at 1098°C (2010°F) for 8 h and then air cooled. This process is repeated at 704°C (1300°F) for 16 h and air cooled, so as to complete precipitation hardening process.

Nimonic 81 can be forged at 1176-1010°C (2150-1850°F).

Nimonic 81 can be hot worked at 1176-1010°C (2150-1850°F). It is better to avoid hot working in the range of 982-538°C (1800-1000°F).

Cold working can be performed using standard tooling. It is better to avoid using plain carbon tool steels for forming as they cause galling. To minimize galling and provide a neat finish, soft die materials containing bronze and zinc alloys are recommended. However, the life of the die is short. Likewise, heavy duty lubricants should be used to reduce galling in all forming operations.

Nimonic 81 can be solution annealed at 1098°C (2010°F) for 8 h .

Nimonic 81 is mainly used in high temperature components of gas turbines.

 

Lork Group is an supplier of industrial metals to the global aerospace, oil and gas, power generation, petrochemical, bio-medical, pharmaceutical, and other high tech manufacturing industries. Products of premium metal products including Inconel alloys,Incoloy alloys,Monel alloys,Haynes alloys,Hastelloy alloy,stainless steelandother superalloy. We certify to most ASME, ASTM, AMS, and military specifications as well as most international standards certification.