Why do F-Cars puff out blue smoke once you replace exhaust with tubi and test pipes?
The interior rust and other oxidation inhibitors are annealing and burning off with the heat from the engine. It disappears in due course but if you dont drive regularly you may notice the tell tale smoke for some time. Take the car to the track and get it really warm and it will be gone!
I replaced my cat & muffler years ago. She has nice white rings inside the exhaust tips showing that she's in perfect health
I believe its the process whereby a material (usually a metal) deposited on another metal is effectively "welded to its surface creating a semi permanent coating. My own experience with this is in aerospace where we often found contaminents annealing themselves to the cooling fins of cylinders or to the hot section of turbines (particularly in choppers) altering their performance, sometimes drastically.
vlamgat, you have absolutely no idea what you're talking about. Where "in aerospace" do you work? It sure as hell better not be metallurgy!
Annealing is a heat treatment process applied to metallic or non-metallic materials (such as glass), where the material is heated and cooled at controlled rates to change the internal molecular structure of the material. It is generally performed to relieve residual stress induced in the material due to manufacturing operations, or to prepare the material for other operations. I know that dirt and chemical contaminants can clog the tiny passages in turbine blades (once worked on a machine for DaimlerChrysler Aero to clean these blades) but it is not annealing in any way. Annealing deals with the internal structure of material, not contaminants deposited on the material surface.
They do this because a small amount of engine oil leaks past the valve guide seals when the engine is not running. so when you first start the engine you burn that oil. some do it more then others just luck of the draw.
I agree with you. But annealing can also occur in uncontrolled environments with random materials. Clearly not all contaminents are going to anneal and usually most do not. but some can and I have seen it all to often on the inside of the hot sections of RR 250 and PT6 engines used in crop spraying. The presence of aluminum and presumably some other materials changes the structure of the metallurgy of the burner can such that when the engine cools, this stuff is impossible to remove with any flushing agent. When we stripped the engines we could not remove the material with a hammer and chisle without breaking the surrounding material. I confess though not to be any type of expert. When the engine parts were returned to RR and BWC of Canada, they told us that the stuff we were spraying had "annealed" itself to our parts and recommended a hot section flush to try and disolve the material before too much of it built up on the inside surfaces. Did'nt work very well and we had to change our SOP. BTW I am a h/c pilot. Stopped counting hours when they got past 12K.
vlamgat, I highly respect anyone who flies a helicopter. That's a lot trickier than any heel-and-toeing most Ferrari drivers do--and we fly in (essentially) only two dimensions! Annealing is ALWAYS a controlled process intended to reduce the brittleness of metal. What you're describing is definitely not annealing. sjb509 nailed the textbook definition. Annealing NEVER fuses metal to metal in any way. I don't mean to give you a hard time personally, but I do get really frustrated by "Technical" responses on Ferrarichat that are based on misunderstanding. I'd like to discourage those posts, and encourage more that have first hand experience, and really know what they're talking about. Please double-check your resources at RR and BWC of Canada. They're way off. --Matt
