Kix,
I think that somebody is confused ;-)
ASTM A1018 is Standard Specification for Steel, Sheet and Strip, Heavy-Thickness Coils, Hot-Rolled, Carbon, Commercial, Drawing, Structural, High-Strength Low-Alloy, High-Strength Low-Alloy with Improved Formability, and Ultra-High Strength Steel. Doesn't look like it comes in round bar...
ASTM A1045 is Standard Specification for Flexible Poly (Vinyl Chloride) (PVC) Gaskets used in Connection of Water Closets to Sanitary Drainage System.
Do you really mean AISI/SAE C1018 and C1045 which are plain low carbon steels with .18 and .45 nominal carbon content respectively?
Regards,