·1136 工程科学学报,第37卷,第9期 贫区 第二相 样品表面 浮凸 MC、N 图10表面浮凸产生机理示意图 Fig.10 lllustration of surface relief formation 奥氏体品界 150m 150m 图11不同钢种的铁素体分布.(a)A钢种:(b)B钢种 Fig.11 Ferrite distribution of experimental steels:(a)steel A:(b)steel B 存在N(C,N)时,先共析铁素体主要沿晶界分布(见 temperature ductility of continuously cast low carbon Nb containing 图11(b). steel slab.ISI/Int,1995,35(1)34 4]Luo H,Karjalainen L P,Porter D A,et al.The influence of Ti on 3结论 the hot ductility of Nb-bearing steels in simulated continuous cast- ing process..1S0t,2002,43(3):273 (1)随着微合金钢钢液的凝固冷却,样品表面会 [5]Kato T,Ito Y,Wamoto M K,et al.Prevention of slab surface 产生细小浮凸,该浮凸出现的温度与分布位置与第二 transverse cracking by microstructure control./S//Int,2003,43 相的析出理论计算及透射电镜表征结果相一致. (11):1742 (2)第二相析出时,其形成原子偏聚或脱溶,导致 Yong Q L,Liu Z D,Sun X J,et al.Theoretical calculation for 第二相析出位置附近局部区域成为微合金元素及C、N equilibrium solubility and compositional coefficient of V(C,N)in 原子的“贫区”,使得该局部区域与周围基体产生比容 V-bearing microalloyed steel.Iron Steel Vanadium Titanium, 2005,26(2):20 差,促使浮凸的产生 (雍岐龙,刘正东,孙新军,等.钒微合金钢中碳氮化钒固溶 (3)通过原位观察表面细小浮凸的产生,可间接 量及化学组成的计算与分析.钢铁钒钛,2005,26(2):20) 表征连续冷却过程中第二相的析出,有利于分析第二 Yong Q L,Chen M X,Pei HZ,et al.Theoretical calculation for 相对基体组织演变的影响. PTT curve of microalloy carbonitride precipitated in ferrite.IIron Steel Res,2006,18(3):30 参考文献 (雍岐龙,陈明昕,裴和中,等.微合金碳氮化物在铁素体中 Szekeres E S.A review of strand casting factors affecting trans- 沉淀析出的PTT曲线的理论计算.钢铁研究学报,2006,18 verse cracking Proceedings of the 6th International Conference (3):30) on Clean Steel.Hungary,2002:324 8] Strid J,Easterling K E.On the chemistry and stability of complex ]Dippenaar R,Moon SC,Szekeres E S.Strand surface cracks: carbide and nitrides in microalloved steels.Acta Metall,1985,33 the role of abnormally large prior-austenite grains.Iron Steel Tech- (11):2057 nol,2007,4(7):105 9]Ma F J,Wen G H,Wang W L.Effect of cooling rates on the sec- B3]Suzuki K.MiyagawaS,Saito Y,et al.Effect of microalloyed ni- ond-phase precipitation and proeutectoid phase transformation of a tride forming elements on precipitation of carbonitride and high Nb-Ti microalloyed steel slab.Steel Res Int,2013,84(4):370工程科学学报,第 37 卷,第 9 期 图 10 表面浮凸产生机理示意图 Fig. 10 Illustration of surface relief formation 图 11 不同钢种的铁素体分布. ( a) A 钢种; ( b) B 钢种 Fig. 11 Ferrite distribution of experimental steels: ( a) steel A; ( b) steel B 存在 Nb( C,N) 时,先共析铁素体主要沿晶界分布( 见 图 11( b) ) . 3 结论 ( 1) 随着微合金钢钢液的凝固冷却,样品表面会 产生细小浮凸,该浮凸出现的温度与分布位置与第二 相的析出理论计算及透射电镜表征结果相一致. ( 2) 第二相析出时,其形成原子偏聚或脱溶,导致 第二相析出位置附近局部区域成为微合金元素及 C、N 原子的“贫区”,使得该局部区域与周围基体产生比容 差,促使浮凸的产生. ( 3) 通过原位观察表面细小浮凸的产生,可间接 表征连续冷却过程中第二相的析出,有利于分析第二 相对基体组织演变的影响. 参 考 文 献 [1] Szekeres E S. A review of strand casting factors affecting transverse cracking / / Proceedings of the 6th International Conference on Clean Steel. Hungary,2002: 324 [2] Dippenaar R,Moon S C,Szekeres E S. Strand surface cracks: the role of abnormally large prior-austenite grains. Iron Steel Technol,2007,4( 7) : 105 [3] Suzuki K,Miyagawa S,Saito Y,et al. Effect of microalloyed nitride forming elements on precipitation of carbonitride and high temperature ductility of continuously cast low carbon Nb containing steel slab. ISIJ Int,1995,35( 1) : 34 [4] Luo H,Karjalainen L P,Porter D A,et al. The influence of Ti on the hot ductility of Nb-bearing steels in simulated continuous casting process. ISIJ Int,2002,43( 3) : 273 [5] Kato T,Ito Y,Wamoto M K,et al. Prevention of slab surface transverse cracking by microstructure control. ISIJ Int,2003,43 ( 11) : 1742 [6] Yong Q L,Liu Z D,Sun X J,et al. Theoretical calculation for equilibrium solubility and compositional coefficient of V( C,N) in V-bearing microalloyed steel. Iron Steel Vanadium Titanium, 2005,26( 2) : 20 ( 雍岐龙,刘正东,孙新军,等. 钒微合金钢中碳氮化钒固溶 量及化学组成的计算与分析. 钢铁钒钛,2005,26( 2) : 20) [7] Yong Q L,Chen M X,Pei H Z,et al. Theoretical calculation for PTT curve of microalloy carbonitride precipitated in ferrite. J Iron Steel Res,2006,18( 3) : 30 ( 雍岐龙,陈明昕,裴和中,等. 微合金碳氮化物在铁素体中 沉淀析出的 PTT 曲线的理论计算. 钢铁研究学报,2006,18 ( 3) : 30) [8] Strid J,Easterling K E. On the chemistry and stability of complex carbide and nitrides in microalloyed steels. Acta Metall,1985,33 ( 11) : 2057 [9] Ma F J,Wen G H,Wang W L. Effect of cooling rates on the second-phase precipitation and proeutectoid phase transformation of a Nb--Ti microalloyed steel slab. Steel Res Int,2013,84( 4) : 370 ·1136·