MUMBAI, India, Oct. 11 -- Intellectual Property India has published a patent application (202517078639 A) filed by Jfe Steel Corporation, Tokyo, on Aug. 19, for 'method for producing high-strength hot-dip galvanized steel sheet.'
Inventor(s) include Tahara Daisuke; Koba Masaki; Hoshino Katsuya; Maeda Satoshi; Tada Masaki; Morimoto Ryohei; and Ono Yoshihiko.
The application for the patent was published on Oct. 10, under issue no. 41/2025.
According to the abstract released by the Intellectual Property India: "The purpose of the present invention is to produce a high-strength hot-dip galvanized steel sheet in which steel to which B has been added is used as a base steel sheet, said hot-dip galvanized steel sheet having a good surface appearance in which the occurrence of gray spot defects and black spot defects on the plated surface has been suppressed. In an annealing step prior to plating, the generation of ammonia and nitriding of the steel sheet are suppressed by lowering the dew point in the 300-500 C temperature range to create an Fe reducing atmosphere, suppressing the generation of iron oxide to suppress the generation of ammonia, and heating quickly to a temperature range at or above 500 C where generation of ammonia becomes prominent and penetration of nitrogen into the steel sheet begins; and the generation of nitrides due to the diffusion of B into the steel sheet surface during annealing is suppressed by also shortening the annealing time in the temperature range at or above 750 C and setting the dew point at -55 C or higher to fix part of the B as an oxide. As a result, the generation of a nitride of B, which is a factor in the formation of gray spot defects and black spot defects, is suppressed."
The patent application was internationally filed on Mar. 18, 2024, under International application No.PCT/JP2024/010576.
Disclaimer: Curated by HT Syndication.
