Metal for diesel exhaust
Metal for diesel exhaust
(OP)
I am working on a project where a housing needs to withstand the diesel exhaust environment. The main hurdle is the temperature (~500 degrees C) because the housing is somewhat isolated from the gaseous part of the environment. I've looked around and found that the most common materials are SS409, Aluminized SS409, and SS304.
Can anyone suggest reasons why one is better (or worse) than the others? Or are there any other materials that I need to consider?
This is an optical application so I need to keep the lens secured at the high temperature so I am also looking for a different material that has a relatively high CTE (>18e-6). How high depends on the CTE of the housing material but that 18e-6 is in the ballpark. Can anyone suggestion options for this?
Thanks,
Dan
Can anyone suggest reasons why one is better (or worse) than the others? Or are there any other materials that I need to consider?
This is an optical application so I need to keep the lens secured at the high temperature so I am also looking for a different material that has a relatively high CTE (>18e-6). How high depends on the CTE of the housing material but that 18e-6 is in the ballpark. Can anyone suggestion options for this?
Thanks,
Dan
Han primo incensus





RE: Metal for diesel exhaust
Have you considered Invar alloy for high temperature stability.
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RE: Metal for diesel exhaust
There are a multitude of alloys to consider, which requires more information about your design and the operating environment.
RE: Metal for diesel exhaust
How will the exhaust system be fabricated? I would assume there is some welding of tubes involved, but will some of the components be cast, or require extensive multi-axis CNC machining, or maybe even be rapid prototyped using DMLS?
You also mentioned a requirement for a material that has a CTE >18ppm/degC. The only readily available corrosion resistant high-temp alloy I can think of that comes close is 304 cres (~17.3ppm/degC). There are some exotic nickel alloys like Carpenter 22-3 or 19-2 that are designed to provide the high CTE you desire (19.8ppm/degC for 22-3 and 20.3ppm/degC for 19-2). While you might be able to use these materials for something like a seal or a bushing, I don't think they would be suitable for constructing the bulk of your diesel exhaust system. Without having more details I would have to agree with CoryPad's inital suggestion of using 304 cres.
Hope that helps.
Terry
RE: Metal for diesel exhaust
If there are areas that get colder, say under 200C then you will need to worry about acid attack.
If you want to go easy, and cost isn't a driver then build it all out of 316L.
Better strength and corrosion resistance than 304, and easy enough to find in many product forms.
You want a high CTE? Doesn't you glass have a much lower CTE? There are special alloys that are designed to match different glasses (902, 903) so you should be able to select one that matches.
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Plymouth Tube
RE: Metal for diesel exhaust
RE: Metal for diesel exhaust
That being said I was originally thinking of using 409 (CTE~13e-6) for the housing and probably 304 (CTE~19e-6) for the spacer. But after reading some of the posts and doing more research I am thinking that aluminized 409 is the better option.
Han primo incensus
RE: Metal for diesel exhaust
Just out of curiosity, what is the purpose of the optical lens in the exhaust system? Is it for measuring the soot in the exhaust gas flow?
RE: Metal for diesel exhaust
Han primo incensus