Originally Posted by gottahaveone

the next time your at an airport and your walking to your jet, note the rotating turbine blades on the engines. these are called "hot rotating parts". if you look at a turbine engine you will quickly understand why it is called "suck and blow"!

air is brought in, fuel is pushed in, it is compressed, and ignition takes place, and thrust is then accomplished, thereby making airplane/boat fly. basics here, ie. turbine 101.

when you look into engine, you see the frontal blades, those and all the other "hot rotating" parts are made of ICONEL 718. usually with a fairly high if not obscene high ROCKWELL HARDNESS!

the base material of iconel is NICKEL!

the next meteorite you happen to see or find, its base material is NICKEL!

nickel is HEAT RESISTANT thereby thats why you find meteorites on occasion, because they have survived the insane heat of rentry thru earths atmosphere.

iconel is very heat resistant, but it is a TOTAL ***** KITTY TO MACHINE as you get into the higher ROCKWELL HARDNESS SCALE.

if you are turning/milling/drilling/threading iconel, you are in for some very high cost tooling because standard tooling (inserts/drills/mills) coated or uncoated will NOT handle repeated tool paths without changing tooling very frequently. in other words you may already have 25 ops on part completed, and if machinist doesnt keep his eyeballs peeled for tool wear it is very easy to scrap part(called a "crash") when insert goes south due to increased wear due to material and its rockwell hardness.

there is a material, to machine iconel available from sandvick(fairlawn,new jersey) called "WHISKERS". this is a man made substance and time doesnt allow me to go into its structure or mfg. process. just suffice it to say its expensive as HELL. but if your doing iconel all day and want to be competitive making parts, bets are on you WILL BE USING it or you will be sucking hind tit, as far as quoting parts, in the jet turbine arena, which is very cutthroat as far as cost per part made, and time spent on part.

so ...............do ya think ya still want stainless valves? apple/apple comparison look up heat resistance of stainless vs. iconel valve. your answer will be obvious. also stainless is about as difficult to machine as butter in comparison to iconel. ie. higher tooling costs for iconel, thereby end user will pay more for iconel valve vs. stainless valve.

as another interesting note.........ICBM missile nosecones are made from ICONEL 718, due to heat factor of rentry into earths atmosphere. ask me how i know all this ?

hope that helps.

Originally Posted by PatriYacht

Mercury Racing has used Inconel in all engines from the Cyclone 454 400hp up.