Bake hardenable steel coated with a water based chromium bearing organic resin.

摘要

A bake hardenable steel sheet ready for deep drawing is coated on at least one side with a continuous chromium bearing epoxy coating. The sheet is roll coated with continuous liquid film containing at least 2 wt.% of a water dispersible or emulsifiable epoxy resin or a mixture of resins containing the epoxy resin, at least 0.5 wt.% of a chromium compound and 25-97 wt.% of water. The liquid coated sheet is induction heated at a temperature of 149-227 DEG C for sufficient time to form a coating resistant to dissolution of chromium and a steel base metal having a yield point elongation no greater than 0.3 % and retaining good bake hardenability characteristics. The chromium bearing epoxy coating is impervious to moisture, can readily be welded and possesses sufficient toughness and lubricity to allow deformation of the sheet without additional external lubricant. A deeply drawn article formed from the sheet has enhanced painting characteristics.