I spoke with my contact at Derale and he informed me that the steel blades of the Derale 18 inch Rigid, Steel-Blade Race Fan - Belt Driven - 8,000 RPM, part # D17318, are made from stamped steel.
If you wanted a fan that features stainless steel blades, and flattens out when sufficient airflow is present, therefore increasing fuel mileage and power I would recommend a Derale 18 inch Heavy-Duty, Stainless Steel Flex Fan, part # D17018. view full answer...