ALEXANDRIA, Va., Dec. 31 -- United States Patent no. 12,509,777, issued on Dec. 30, was assigned to NIPPON STEEL Corp. (Tokyo).
"Surface-treated steel sheet" was invented by Atsuo Shimizu (Tokyo), Ikumi Tokuda (Tokyo) and Hiromasa Shoji (Tokyo).
According to the abstract* released by the U.S. Patent & Trademark Office: "A surface-treated steel sheet including a steel sheet, a zinc-based plated layer, and a chemical conversion treatment layer that contains Si, C, O and P, and has a C concentration of 20.0 mass % or more, an O concentration of 15.0 mass % or more, a Si concentration of 10.0 mass % or more, and a P concentration of 0.10 mass % or more. When t is a thickness of the chemical conversion treatment layer, an area from a surface t...