Steelmaking Production Practice of 9Ni Steel for Ulta-low Temperature Pressure Vessel

• Published in: Te shu gang Vol. 45; no. 1; pp. 27 - 32
• Main Author: Zhang Tianshu, Huang Zhicheng, Chi Yunguang, Yang Jian
• Format: Journal Article
• Language: Chinese
• Published: Editorial Office of Special Steel 01.01.2024
• Subjects: 9ni steel， dephosphorization； decarbonization； scraping slag； fetching slag
• ISSN: 1003-8620
• DOI: 10.20057/j.1003-8620.2023-00174

This article presents the smelting practice of 9Ni steel for ultra-low-temperature pressure vessel in a certain steel plant by the "BOF → LF → scraping slag/fetching slag → LF → VD → CC" process. The decarburization and desulfurization in the BOF + LF process require that the steel produced by the converter has a low phosphorus （w［P］） ≤ 0.009%） and carbon content （w［C］） ≤ 0.05%）， with an average desulfurization rate of 74.3% and an average decarburization rate of 51.2%. The control of phosphorus content is more difficult than carbon content in the production process. In the scraping slag process， the average phosphorus reversion rate in the molten steel is 16.89%， while in the fetching slag process， it is 22.61%. Although the scraping slag process results in a lower phosphorus reversion rate in the molten steel， the processing time is increased by 15 to 20 minutes， and the average molten steel loss is increased by 3.1 t per heat. After adjusting the addition of nickel plates from the converter to the ladle fu