Nickel alloy 718 is one of the most popular nickel-based superalloys for use in gas engines. It is a high-strength, corrosion and oxidation-resistant nickel-chromium alloy with excellent tensile and fatigue properties at both elevated temperatures and cryogenic temperatures. It has high creep resistance, thermal fatigue resistance and ductility. It also has good oxidation resistance at both hot and cold temperatures and is widely used in applications such as gas turbine blades, turbine vane and other components that require a high strength-to-weight ratio.
Typical applications include valves and precision tubing for liquid fueled rockets, various formed sheet metal parts for aircraft and gas turbine engines, cryogenic tankage, and fasteners. It is also suitable for use in the marine environment where it is resistant to acids, sea water and sour oil or gas.
Precipitation hardenable nickel-chromium alloy with excellent oxidation and corrosion resistance at both high temperatures and cold, as well as high strength and creep rupture properties up to 1300deg F (700deg C). It is non-magnetic and maintains excellent resistance to stress corrosion cracking, phosphate attack, chloride pitting and hydrogen induced deterioration.
It is typically available in the form of bars, forgings, sheets and plates. It is heat treated to give maximum tensile and creep resistance with hardness values usually exceeding 42 HRC.
Electrical discharge machining is an effective method to machine Inconel® superalloy. Using the right electrode material, current settings and process parameters, it is possible to achieve very good dimensional shape accuracy and to improve material removal. However, a number of issues should be considered, such as the material's thermophysical properties and the gap area during electrical discharge machining, to ensure that the best hole accuracy is achieved.