Coeficient of expansion of Cast Iron vs Bolts

[Darkman270]

What is the coeficient of expansion of Cast Iron such as used in engine heads?

What type and grade of bolt would come close to matching the Cast iron?

 

[gdodd]

Coefficient of thermal expansion for cast iron is 6 x 10 power-6 in/in/degree F.
Carbon steel COTE is 8 to 8.4 x10 power-6 in/in/degree F depending on carbon content.

If you want something with a figure close to cast iron then I suggest you use a ferritic grade of stainless steel such as 405 or 430 which have a COTE of 6 and 5.8 x 10 power-6 in/in/degree F respectively.