Enhancing mechanical properties of Inconel 718 for aerospace applications
Advanced aircraft applications demand more reliable materials due to widely innovative technology. Designs are based on fuel efficiency and consistency. In addition to commercial uses, military based defense operations widely rely on the extreme performance of the aircraft engines. To receive the maximum performance at economical price, aerospace applications involve the use of components made from Inconel 718 and other high nickel super alloys.
Combustion engines in aircrafts use Inconel 718 for hot sections of turboreactors. It is a heat resistant material that can withstand severe mechanical stress and pressure in vigorous conditions while offering reliable performance and corrosion resistance.
Service in critical conditions
Inconel 718 is specifically suitable for function in high temperature conditions that demand resistance to creeping, corrosion and thermal shock. Usually this type of Nickel alloys can be hardened by solid solution strengthening or precipitation.
Inconel 718 has become a popularly used alloys because of its deployment in numerous applications. It is a refractory super alloy as it can perform above 600oC. It has good creep and rupture strength with supreme fatigue resistance. It retains its high strength and toughness at higher temperature along with corrosion resistance to elevated temperatures.
For its an extensive range of properties, Inconel 718 is used several components of aircraft turbojet engines such as discs, blades, cases of high pressure region of compressor. It is also used in rocket engines and cryogenic conditions.
Inconel 718’s key composition
Presence of iron in Inconel 718 creates a precipitation hardening effect. It helps creating a main strengthening phase, a slow precipitation mechanism that prevents sensitivity to after- weld cracking. The alloy is also resistant to corrosion to 1000oC. Nickel in Inconel 718 offers resistance to chloride ion stress corrosion cracking and secures from corrosion in various inorganic and organic oxidizing compounds in many acidic and alkaline conditions. Chromium prevents corrosion in oxidizing media and sulfur compounds. Besides, Molybdenum improves pitting resistance.
The strengthening modes such as solid solution hardening and precipitation hardening are followed to improve the strength of Inconel 718.
Nickel based alloy Inconel 718 offers excellent mechanical properties at the elevated points. Although it is tough to machine for its high shear strength, and low thermal conductivity, the presence of carbide particles in its microstructure, it causes quick tool damage. Machining based residual stresses in a machined component is an essential factor which is evaluated as it can be implemented to determine the overall structure resilience of the component. Ultrasonically based turning is found to be successful in which a tool and material interaction conditions are modified by imposing ultrasonic vibration on a tool’s motion during cutting. Although complete information of residual stresses created during this process is not available. Various studies show that Ultrasonically assisted turning results into considerable reduction in cutting forces and enhanced surface roughness in comparison to traditional turning for cutting speeds below a critical value. This process creates larger compressive stress as compare to conventional turning, meanwhile overall enhancement in properties of Inconel alloys.