374 东 北 大 学 学 报 ( 自 然 科 学 版 ) 第 34 卷 A A = A i 100 = PP i 100 A T PP T 1 1 A A % A i mm 2 A T mm 2 PP i 1 1 PP T 80 t 120 t RH 80 t 55SiCrA 120 t Q690

第 34 卷 第 3 期 2013 年 3 月 东 北 大 学 学 报 ( 自 然 科 学 版 ) Journal of Northeastern University( Natural Science) Vo l 34,No 3 Mar 2 0 1 3 RH 王 德 永, 吕 铭, 刘 承 军, 姜 茂 发 110819 RH SEM RH RH 10 μm RH RH TF 77 A 1005-3026 2013 03-0373 - 05 The Evolution and Behavior of the Non-metallic During the RH Refining Process Inclusions WNAG De-yong L Ming LIU Cheng-jun JIANG Mao-fa School of Materials & Metallurgy Northeastern University Shenyang 110819 China Corresponding author WANG De-yong E-mail wangdy@ smm neu edu cn Abstract Two sets of RH furnaces were taken as the main objects The specimens were sampled at different refining times The composition content and size distribution of the inclusions in steels were analyzed by means of metallographic microscope SEM and EDS and the collision growth and removal of the inclusions during RH refining process were discussed The results showed that the inclusion removal was very obvious during RH refining process and almost no inclusion with the dimension more than 10 μm were observed after the soft blowing With the increase of refining time the average size of inclusions changed little however the amount of inclusions significantly decreased The area ratio of inclusions in two type steels increased at first and then reduced In Si-Mn deoxidized steels silicate inclusions had a certain capacity of the sulphur the dual layer inclusions were therefore easier to form with the surface of sulphur-rich phase and the inner core of silicate phase As the strong mixture of the liquid steel in RH vacuum chamber solid inclusions were always captured by the liquid calcium aluminate and formed a typical inlaid feature Key words RH refining non-metallic inclusions evolution removal inlaid feature RH 1 - LF 3 80 t 120 t RH SEM /EDS RH BOF RH CC RH 2012-08 - 22 50904017 2011M500823 1974-1974 - 1955 -

374 东 北 大 学 学 报 ( 自 然 科 学 版 ) 第 34 卷 A A = A i 100 = PP i 100 A T PP T 1 1 A A % A i mm 2 A T mm 2 PP i 1 1 PP T 80 t 120 t RH 80 t 55SiCrA 120 t Q690D ipp 6 0 55SiCrA BOF 2 LF RH CC Si - Mn - Al SSX - 550 LF CaC 2 RH 120 Pa 20 min 15 min Q690D BOF LF RH CC Al RH RH 50 Pa 20 min 10 min 1 2 RH 3 ~5 min RH 2 10 μm 400 mm 2 2 3 1 /2 10 mm 6 mm 1 3 2 2 1 RH 55SiCrA 1 3 55SiCrA RH RH 1 94 μm 3 35 μm Olympus BX51 0 ~ 5 μm 93 86% Miki 4 RH 200 64 551 472 μm 2 ipp6 0 Stokes 55SiCrA RH 3 39 5 /mm 2 3 27 3 /mm 2 ipp6 0 r i r j 5 N ij Fig 1 1 55SiCrA 3 The change of inclusions in 55SiCrA spring steels during RH refining process the average value for 3 heats a b c

第 3 期 王 德 永 等 : RH 精 炼 过 程 钢 中 非 金 属 夹 杂 物 行 为 及 演 变 规 律 375 N ij = β r i r j n r i n r j 2 β r i r j n r i 10 μm n r j r i r j m -3 2 55SiCrA 2 RH Ca Al Mg Si O 10 μm S 2a 2e 2g 2h RH 2b 2c 2f 1b MnS RH 55SiCrA CaS 0 023% 0 057% 0 011% 52 17% RH 10 μm 6 ~ 10 μm 2g 3 min Fig 2 2 55SiCrA RH SEM SEM images of the inclusions in 55SiCrA spring steels during RH refining process a ~ b RH c ~ d 3 min e ~ g h ~ j 2 2 RH Q690D RH 1 72 μm 3 Q690D RH 1 9 μm RH 55 6 /mm 2 29 4 / mm 2 Fig 3 3 Q690D RH 3 The change of inclusions in Q690D steels during RH refining process the average value for 3 heats a b c

376 东 北 大 学 学 报 ( 自 然 科 学 版 ) 第 34 卷 RH 0 023% 4d 4g 2 ~ 3 μm 0 030% 0 015% D 34 78% 10 μm Al MgO 6 2 ~ 5 μm 18 70% 37 76% 2 Al + 4MgO slag /ref = MgAl 2 O 4 + 3Mg g 2 16 75% RH 4 Q690D 7-9 10 Mg10-6 Fig 4 4 Q690D RH SEM SEM images of the inclusions in Q690D steels during RH refining process a ~ b RH c ~ f 5 min g ~ h i ~ j 4c 5a 4e 4f 4h 3 ~ 5 μm CaO - MgO - Al 2 O 3 FactSage 1 600 RH 5b RH Fig 5 5 The formation mechanism of the dual-phase inclusion in this present work a b

第 3 期 王 德 永 等 : RH 精 炼 过 程 钢 中 非 金 属 夹 杂 物 行 为 及 演 变 规 律 377 3 1 RH 10 μm RH 24 8 31-38 5 J Shu Zhi-hao 2 Si - Mn - 120 3 RH RH 9 Jo S K Kin S H Song B Thermodynamics on the formation of 1 RH spinel MgO Al 2 O 3 inclusion in liquid iron containing J 1996 31 1 26-30 Jin Da-zhong Dong Jin-sheng Lu Lian-fang et al Effect of RH treatment on low carbon Al-killed steel cleanliness J Iron and Steel 1996 31 1 26-30 2 RH-KTB 1996 12 1 53-59 RH J Zhang Chun-xia Liu Liu Du Ting A survey of RH vacuum refining process J Steelmaking 1996 12 1 53-59 3 Matsuno H Kikuchi Y Komatsu M et al Development of a new deoxidation technique for RH degassers J Iron and Steelmaker 1993 20 7 35-38 4 Miki Y Shimada Y Thomas B G Model of inclusion removal during RH degassing of steel J Iron and Steelmaker 1997 2009 31 1 118-120 Cheng Shu-sen Zhao Jing-jing et al Inclusion coagulation and removal rate in molten steel J Journal of University of Science and Technology Beijing 2009 31 1 118 6 Itoh H Hino M Ban-ya S Deoxidation equilibrium of magnesium in liquid iron J Tetsu-to-Hagané 1997 83 10 623-628 7 Itoh H Hino M Ban-ya S Thermodynamics on the formation of spinel nonmetallic inclusion in liquid steel J Metallurgical and Materials Transactions B 1997 28 10 953-956 8 Itoh H Hino M Ban-ya S Thermodynamics on the formation of non-metallic inclusion of spinel MgOAl 2 O 3 in liquid steel J Tetsu-to-Hagané 1998 84 2 85-90 chromium J Metallurgical and Materials Transactions B 2002 33 10 703-709 10 Katsumori F Tetsuya N Mitsutaka H Activities of the constituents in spinel solid solution and free energies of formation of MgO MgO Al 2 O 3 J ISIJ International 2000 40 11 1059-1066