MUMBAI, India, Oct. 11 -- Intellectual Property India has published a patent application (202517078661 A) filed by Jfe Steel Corporation, Tokyo, on Aug. 19, for 'method for manufacturing 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: "This high-strength, hot-dip galvanized steel sheet having a favorable surface appearance and in which the occurrence of gray spot defects and black spot defects in a plating surface thereof are suppressed is manufactured by using, as a base material steel sheet, steel to which B has been added. In an annealing step prior to plating, an Fe reducing atmosphere is created by lowering the dew point to a temperature range of 300-500 C to achieve suppression of generation of iron oxide and thereby suppress generation of ammonia. Furthermore, heating to a temperature range of 500 C or higher, which is the range in which generation of ammonia becomes noticeable and penetration of nitrogen into the steel sheet starts, is carried out rapidly to thereby suppress generation of ammonia and nitridization of the steel sheet. Also, the annealing time at a temperature range of 750 C or higher is shortened and the dew point is set to -55 C or higher to fix a portion of the B as an oxide to thereby suppress the generation of a nitride resulting from the diffusion of the B to the steel sheet surface during annealing. As a result, generation of a nitride of B, which is a factor in the occurrence 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/JP2024/010575.
Disclaimer: Curated by HT Syndication.
