A true seasoned surface will only form properly at temperatures well in excess of the 350-375 degree F temperature that some manufacturers recommend for seasoning cast iron. Low temperatures do not completely polymerize and break down oil and will leave a brown, somewhat sticky pan instead of a black, non-stick one. 400-500 degrees F is the effective range for seasoning.

From Dave Arnold’s excellent blog ‘Cooking Issues’

https://cookingissues.com/2010/02/16/heavy-metal-the-science-of-cast-iron-cooking/