Thermal expansion co-efficient of EN-AC-AlSi7Mg0.3 ST6 at -40 deg C ?

[srimanishreddy]

Hello every one,

My question deals with a project replacing a cast iron housing (EN-GJL 250) with aluminium cast (EN-AC-AlSi7Mg0.3 ST6) housing. I am calculating the fit geometries for the new material housing based on its material thermal expansion properties. The housing has extreme temparature working conditions scaling from -40 to 110 deg Celcilus. From DIN 1706, I could find the mean thermal co-efficient value for the mentioned material from 20 to 100 deg C, but couldnot find the values for 110 and -40 deg Celcius. Any know-how to share regarding these values or topic would be a great help.

ideas on when a linear and cubic thermal expansion co-efficient should be used to calculate the fit geometries would be great.

thanks,
Enakonda

 

[EdStainless]

I would suggest just looking at generically similar alloys to decide on how to extend the range.
For the cast iron you know that as you go to higher temp the CTE increases slightly, though the difference between 100 and 110 will be insignificant. And as you go to slightly lower temp the CTE will decrease slightly.
I am not sure about the Al though.

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P.E. Metallurgy