Nickel superalloys of the Inconel family retain strength and resist oxidation at temperatures that defeat steels, which is why they end up in turbines, exhausts, heat exchangers and combustion hardware. They are also expensive and notoriously difficult to machine, which is exactly the profile that makes additive manufacturing attractive.
Why it suits printing
The alloy is expensive per kilogram and slow to cut, so a machined part throws away costly material through many hours of tooling. Building near net shape saves both. The parts themselves are usually complex, low volume and often carry internal cooling passages, which is precisely the geometry additive does well and machining does not.
The printable grades
The solid solution strengthened grades print readily and are the common choice for exhaust, ducting and heat exchanger work. The precipitation hardened grades reach much higher strength after heat treatment and are more prone to cracking during the build, so their parameters are more sensitive. Which grade is available depends on the supplier as much as on the machine.
Heat treatment and stress
Nickel superalloys develop substantial residual stress in a build because of their strength at temperature. Stress relief before removal from the plate is essential. For the precipitation hardened grades, a full solution and ageing treatment is what produces the properties the alloy was chosen for, and hot isostatic pressing is common where fatigue governs.
Machining what has to be accurate
Every fit, flange face and threaded feature is machined after printing, and machining Inconel is as slow and expensive as it always was. That is a good argument for designing the part so as little as possible needs machining, and for making sure the printed part carries a fixturing datum that the machinist can actually use.
Questions people ask about 3d printing inconel
Why print Inconel rather than machine it?
Because the alloy is expensive and very slow to cut, so near net shape saves both material and many hours of machining, and the parts are usually complex and low volume.
Which Inconel grades can be printed?
Solid solution strengthened grades print readily. Precipitation hardened grades reach higher strength after heat treatment and are more sensitive during the build.
What heat treatment is needed?
Stress relief before plate removal in all cases, plus solution treatment and ageing for precipitation hardened grades, and hot isostatic pressing where fatigue governs.
Does a printed Inconel part still need machining?
Yes, on every accurate feature. Machining Inconel remains slow and costly, so design to minimise it and provide a usable fixturing datum.