MUMBAI, India, Sept. 26 -- Intellectual Property India has published a patent application (202517085638 A) filed by Jfe Steel Corporation, Tokyo, on Sept. 9, for 'method for producing high-strength hot-dip galvanized steel sheet.'
Inventor(s) include Yamamoto Shunsuke; Kanazawa Tomomi; Tamaki Shogo; Hoshino Katsuya; Takashima Katsutoshi; and Sawanishi Chikaumi.
The application for the patent was published on Sept. 26, under issue no. 39/2025.
According to the abstract released by the Intellectual Property India: "Provided is a method for producing a high-strength hot dip galvanized steel sheet which has excellent LME cracking resistance and suppresses deterioration of delayed fracture resistance caused by hydrogen embrittlement while ensuring appearance quality of the steel sheet. The method for producing the hot-dip galvanized steel sheet according to the present invention applies oxidation treatment to a steel sheet containing a predetermined amount of Si, applies reduction annealing, and then applies hot dip galvanizing. The oxidation treatment is performed at a temperature of 500 C-800 C in an atmosphere containing N2 and 500 ppm by volume or more of O2. The reduction annealing is executed by first reduction annealing at a former stage which holds the steel sheet at a predetermined temperature for a predetermined time in an atmosphere having the dew point at -45 C to +20 C and containing 5.0%-25% by volume of hydrogen and N2 as the balance; and second reduction annealing at a latter stage which holds the steel sheet at a predetermined temperature for a predetermined time in an atmosphere having the dew point at -10 C to +20 C and containing 2.0%-8.0% by volume of hydrogen and N2 as the balance. Moreover, the hydrogen concentration in the first reduction annealing at the former stage is adjusted so as to be higher than the hydrogen concentration in the second reduction annealing at the latter stage."
The patent application was internationally filed on Apr. 28, 2023, under International application No.PCT/JP2023/016785.
Disclaimer: Curated by HT Syndication.
