Manufacturing of 9CrMoCoB Steel of Large Ingot with Homogeneity by ESR Process

International Symposium on Liquid Metal Processing & Casting 2015

材料科学;金属工艺学

Kim, D.S.^1 ; Lee, G.J.^1 ; Lee, M.B.^1 ; Hur, J.I.^1 ; Lee, J.W.^1

Casting and Forging BG, Doosan Heavy Industries and Construction, 22, DoosanVolvo-ro, Seongsan-gu, Changwon, Gyeongnam

642-792, Korea, Republic of^1

关键词: CaO-Al2O3-SiO2;    Equilibrium relations;    ESR process;    Large ingot;    Oxygen content;    Si content;    Slag system;    Thermodynamic equilibria;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/143/1/012002/pdf
DOI  :  10.1088/1757-899X/143/1/012002

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

In case of 9CrMoCoB (COST FB2) steel, equilibrium relation between [B]/[Si] ratio and (B2O3)/(SiO2) ratio is very important to control [Si] and [B] in optimum range. Therefore, in this work, to investigate the thermodynamic equilibrium relation between [B]/[Si] ratio and (B2O3)/(SiO2) ratio, pilot ESR experiments of 9CrMoCoB steel were carried out using the CaF2-CaO-Al2O3-SiO2-B2O3slag system according to change of Si content in electrode and B2O3content in the slag. Furthermore, through the test melting of the 20ton-class ESR ingot, the merits and demerits of soft arcing were investigated. From these results, it is concluded that oxygen content in the ESR ingot decrease with decreasing SiO2content in the slag, relation function between [B]/[Si] ratio and (B2O3)/(SiO2) ratio derived by Pilot ESR test shows a good agreement as compared to the calculated line with a same slope and soft arcing makes interior and surface quality of ingot worse. With the optimized ESR conditions obtained from the present study, a 1000mm diameter (20 tons) and 2200mm diameter (120ton) 9CrMoCoB steel of the ESR ingot were successfully manufactured with good homogeneity by the ESR process.