a member made of steel will generally be more rigid than a member of equal load-carrying ability made of cast iron

a member made of cast iron will generally be. more rigid than a member of equal load carrying ability made of steel

both will be equally rigid

which one is rigid will depend on several other factors

Young′s modulus

coefficient of elasticity

elastic limit

endurance limit.

low

zero

high

could be anything

0.33

0.4

0.5

0.55

same

1-Feb

1-Mar

2-Mar