Creep of aluminium cylinder heads
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From: Munich, Germany
Creep of aluminium cylinder heads
I am currently learning for a test in materials engineering and just came to a chapter that treats creep.
Well we've learned in lecture that creep of a material starts at about 2/5 of it's melting temperature. With the melting temperature of Aluminium being at about 660 °C, the temperature where creep starts would be right at 264°C, which pretty sure is exceeded in an engine. (please correct me if I'm wrong)
Now my question is, how the engineers developing the aluminium heads forestall this phenomenon. Do they use any alloying components to raise the melting temperature, or is creep not relevant for cylinder heads, because there's not a static load stressing them?
Sorry for the long and kind of boring post, but I thought discussing it here would make learning more fun
Actually I guess I've memorized a lot just by writing this 
Well we've learned in lecture that creep of a material starts at about 2/5 of it's melting temperature. With the melting temperature of Aluminium being at about 660 °C, the temperature where creep starts would be right at 264°C, which pretty sure is exceeded in an engine. (please correct me if I'm wrong)
Now my question is, how the engineers developing the aluminium heads forestall this phenomenon. Do they use any alloying components to raise the melting temperature, or is creep not relevant for cylinder heads, because there's not a static load stressing them?
Sorry for the long and kind of boring post, but I thought discussing it here would make learning more fun
Actually I guess I've memorized a lot just by writing this
Last edited by dancutlass; Jan 17, 2013 at 12:18 PM.
Connoisseur d'Junque
Joined: Sep 2010
Posts: 21,183
From: The Hudson Valley
Well, 264°C is 507°F, and though I would expect that the inner surfaces of the combustion chambers experience temperatures this high, I believe that the coolant carries the heat away quickly enough that only a fairly thin layer of material directly lining the combustion chamber sees it, and that only for milliseconds, as the new mixture charge is much cooler as it enters the chamber with the next cycle.
- Eric
- Eric
Old(s) Fart
Joined: Mar 2007
Posts: 50,802
From: Northern VA
Well, 264°C is 507°F, and though I would expect that the inner surfaces of the combustion chambers experience temperatures this high, I believe that the coolant carries the heat away quickly enough that only a fairly thin layer of material directly lining the combustion chamber sees it, and that only for milliseconds, as the new mixture charge is much cooler as it enters the chamber with the next cycle.
- Eric
- Eric
'87 Delta 88 Royale
Joined: Dec 2010
Posts: 2,514
From: Margate, England
Pure aluminium (as we call it over here) melts at 660c, but the metal used in engines and most other applications is alloyed with other materials to add toughness, raise the melting point etc.
How cold is too cold?,
During WW2 the Germans fighting on the eastern front had a lot of problems getting there equipment to work in -40 temperatures, tires and metal often shattered in such extreme conditions. They had to run their vehicles every hour or so just to keep them operable.
Roger.
How cold is too cold?,
During WW2 the Germans fighting on the eastern front had a lot of problems getting there equipment to work in -40 temperatures, tires and metal often shattered in such extreme conditions. They had to run their vehicles every hour or so just to keep them operable.
Roger.
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