Aluminum Alloy for high temp engine service

[RoarkS]

Howdy metal fellas, I could use a point in the right direction. Been working on a similar post in Aerospace but thought materials might know a bit or two also.

I have an air cooled reciprocating engine head that was made from "Alcoa 142-t63/Bohn Y-2 Heat treat:30000 min tensile, 2-3% elongation, appx 70 brinell" in the early 1940's. I have the AMS spec sheet from 1955 for A142-t77.

Lists equivalents... the ones that I seem to find the most of are AMS4220 AMS4222. All of these specs have been cancelled.

In MIL-HDBK-5, AMS-A-21180 Casting (T7 temper), is the highest temp alloy I can find... it lists data at 350°F... not quite hot enough.

What would I make a 475°F max design temp cylinder head out of with all of the related alloys that I can find being cancelled?

 

[tbuelna]

RoarkS-

I don't know of any aluminum alloys, wrought or cast, that have a safe service temp capability of 475degF. As you noted A201-T7 is a high-temp casting alloy, but it cannot be sand cast. There are some wrought alloys, such as 2219, that can endure brief exposure to 475degF, but long term exposure to this temp may result in creep.

Hope that helps.
Terry

 

[swall]

Found some old data for sand cast 201-T7 from when I was involved with this stuff back in the '80's. 400F UTS is 39ksi, TYS is 33ksi. At 500F, UTS is 16ksi, TYS is 13ksi. Also found a fatigue limit of 12 ksi at 400F.

 

[dgallup]

It's my understanding that the industry has moved to hypereutectic aluminum alloys for cast pistons with higher temperature limits. Should work for heads but I'm no expert.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[RoarkS]

Thought I would share, I heard back from a foundry that does flight critical components, they shared with me that most air cooled cylinder heads are A242 alloy. Still trying to work out a temper...