。360· 北京科技大学学报 2006年第4期 体晶粒，在过冷度允许奥氏体转变成针状铁素体 3219 之前，晶界多边形铁素体大量形成，抑制晶内针状 [2 Tomita Y,Saito N.T suzuki T,et al.Impmovement in HAZ toughness of steel by TiN-MnS addition.ISIJ Int 1994,34: 铁素体形成.所以氧化物尺寸的影响实质上是晶 829 界相竞争反应的表现 3 Homma H.OhkitaS MatsudaS,e al.Improvement of HAZ 其次，从实验结果来看：在合适氧化物上直接 toughness in HSLA steel by int roducing finely dispersed Ti-ox- 形成针状铁素体可以被看成是一种氧化物与基体 ide.Weld,1987,66:301 近旁点阵畸变的行为，由于它有非常高的畸变（达 [4 Yamamoto K.Hasegaw a T,Takamura J.Effect of boron on 30%)y,则围绕氧化物出现高密度位错，为针状 intra-granuar ferrite fomation in Troxide bearing steels.ISIJ 1nt199636:80 铁素体提供了形核位置.所以，氧化物尺寸过小 [5]Mabuchi H.Uemori R.Fujioka M.Role of Mn depletion in 或过大对产生晶格畸变或位错密度都是不利的， intra-granular ferrite trandfomation in the heat affected zone of 氧化物尺寸在0.1~0.6m范围时形核效果最佳. welded joints with large heat input in structural steels.ISIJ 1nt1996.36:1021 3结论 [6 Enomoto M,Sonoyama T,Yada H.Kinetics of austenite to (1)晶内针状铁素体板条可以在氧化物上形 ferrite transformation in 3 mass%Mn low carbon steels. Mater Trans.1998 4:189 核，同时形成大量新的奥氏体/铁素体高能内界 【刀Gregg J M,Bha止shia H K D H.Solidstate ruceat ion of aci- 面，并在内界面上发生激发形核现象 cular ferrite on mirerals added to molten steel.Acta Mater, (2)氧化物基体之间弹性模量和热膨胀系 1997,45:739 数不同，冷却过程中氧化物近旁产生应变场.此 [8 Zhang Z.Farrar R A.Role of nommetalic inclusions in for 应变区的存在是晶内针状铁素体形成的主要控制 mation of acicular ferrite in low alloy weld metal.Mater Sci Technol,1996.12:237 因素. [9 Zhang S,Hattori N.Enomoto M.et aL.Ferrite nuckation at (3)氧化物尺寸分布决定了形核地点的有效 ceramid/aust enite interfaces.ISIJ Int 1996 36:1301 性，氧化物尺寸在0.1~0.6m范围时对促进针 [10]Farar R A,Harrison P L.Acicular ferrite in carborrmar 状铁素体形成效果最好. ganese weld metals an overview.J Mater Sci.1987,22: 3812 参考文献 11]Ricks R A.Howel P R.Barritte G S.The nature of acialar [1]Lee J L.Evaluation of the nucleation pot ential of intrag marular ferrite in HSLA steel weld metals J Mater Sci 1982.17:732 acicular ferrite in steel weldments.Acta Metall.1994,42: Nucleation of intragranular ferrite at oxide particles in low carbon steel PU Yong2.HU Benfu,YIN Fazhang,CHEN Xiao 1)Materiak Science and Ergineering School University of Science and Technology Beijing,Beijing 100083 China 2)Wuhan I rn and Steel (Gmoup)Co.,Wuhan 430080.China ABSTRACT The intragranular nucleation phenomena of ferrite in bw carbon steels with oxides of CaO and Ce02 were studied using a method of hot diffusion bonding.The experimental results show ed that the fine intragranular acicular ferrite structure in low carbon steels with oxides of CaO and Ce02 was induced by heterogeneous nucleation of ferrite plates at fine dispersed Cao and Ce02 particles.There were large ther- mally induced strain regions in the neighbourhood of Cao and Ce02.The presence of these regions provided dominant driving force for the nucleation of acicular ferrite,which led to multiple nucleations on the inclu- sion.Meanw hile a large quantity of new austenite/ferrite high energy interfaces formed,which provided the surface effect of the sym pathetical nucleation.The optimum size of oxides for adequate nucleation of aci- cular ferrite was 0.I to 0.6/m. KEY WORDS low carbon steel;oxide;acicular ferrite;hot diffusion;microstructure体晶粒 ,在过冷度允许奥氏体转变成针状铁素体 之前 ,晶界多边形铁素体大量形成 ,抑制晶内针状 铁素体形成.所以氧化物尺寸的影响实质上是晶 界相竞争反应的表现 . 其次 ,从实验结果来看:在合适氧化物上直接 形成针状铁素体可以被看成是一种氧化物与基体 近旁点阵畸变的行为 ,由于它有非常高的畸变(达 30 %) [ 9] ,则围绕氧化物出现高密度位错 ,为针状 铁素体提供了形核位置.所以, 氧化物尺寸过小 或过大对产生晶格畸变或位错密度都是不利的, 氧化物尺寸在0.1 ～ 0.6 μm 范围时形核效果最佳. 3 结论 (1)晶内针状铁素体板条可以在氧化物上形 核,同时形成大量新的奥氏体/铁素体高能内界 面,并在内界面上发生激发形核现象. (2)氧化物/基体之间弹性模量和热膨胀系 数不同, 冷却过程中氧化物近旁产生应变场 .此 应变区的存在是晶内针状铁素体形成的主要控制 因素 . (3)氧化物尺寸分布决定了形核地点的有效 性,氧化物尺寸在 0.1 ～ 0.6 μm 范围时对促进针 状铁素体形成效果最好. 参 考 文 献 [ 1] Lee J L .Evaluation of the nucleation pot ential of intrag ranular acicular ferrit e in st eel w eldments.Acta Metall , 1994 , 42: 3219 [ 2] Tomit a Y , Saito N , T suzuki T , et al.Improvemen t in HAZ toughness of steel by TiN-MnS addition.ISIJ Int, 1994 , 34: 829 [ 3] Homma H , Ohkit a S , Matsuda S , et al.Improvement of HAZ toughness in HS LA steel by introducing finely dispersed Ti-ox￾ide.Weld J , 1987 , 66:301 [ 4] Yamamot o K , Hasegaw a T , Takamura J.Eff ect of boron on intra-granular f errit e formation in Ti-oxide bearing steels.ISIJ Int, 1996 , 36:80 [ 5] Mabuchi H , Uemori R, Fujioka M .Role of Mn depletion in intra-granular f errite transf ormation in the heat affected zone of w elded joints with large heat input in structural steels.ISIJ Int, 1996 , 36:1021 [ 6] Enomoto M , Sonoyama T , Yada H .Kinetics of austenit e t o f errit e transformation in 3 mass% Mn low carbon steels. Mater Trans, 1998 , 4:189 [ 7] Gregg J M , Bhadeshia H K D H .Solid-st at e nucleation of aci￾cular ferrite on minerals added to molten st eel.Acta Mater , 1997 , 45:739 [ 8] Zhang Z , Farrar R A.Role of non-metallic inclusions in f or￾mation of acicular ferrit e in low alloy w eld metals.Mater Sci Technol , 1996 , 12:237 [ 9] Zhang S , Hatt ori N , Enomot o M , et al.Ferrit e nucleation at ceramic/ aust enit e interf aces.ISIJ Int, 1996 , 36:1301 [ 10] Farrar R A , Harrison P L .Acicular ferrit e in carbon-man￾ganese w eld metals:an overview .J Mater Sci, 1987 , 22: 3812 [ 11] Ricks R A, How ell P R, Barritt e G S .The nature of acicular f errite in HS LA steel w eld metals.J Mater Sci, 1982 , 17:732 Nucleation of intrag ranular ferrite at oxide particles in low carbon steel PU Yong 1 , 2), HU Benfu 1), Y IN Fazhang 1), CHEN Xiao 2) 1)Materials Science and Engineering School, University of Science and Technology Beijing , Beijing 100083 , China 2)Wuhan I ron and St eel(Group)Co ., Wuhan 430080 , China ABSTRACT The intrag ranular nucleation phenomena of ferrite in low carbon steels w ith oxides of CaO and CeO2 were studied using a method of hot diffusion bonding .The experimental results show ed that the fine intrag ranular acicular ferrite structure in low carbon steels with oxides of CaO and CeO2 was induced by heterogeneous nucleation of ferrite plates at fine dispersed CaO and CeO2 particles .There were large ther￾mally induced strain regions in the neighbourhood of CaO and CeO2 .The presence of these regions provided dominant driving force for the nucleation of acicular ferrite , w hich led to multiple nucleations on the inclu￾sion .Meanw hile a large quantity of new austenite/ ferrite high energy interfaces fo rmed , w hich provided the surface effect of the sympathetical nucleation .The optimum size of oxides for adequate nucleation of aci￾cular ferrite w as 0.1 to 0.6 μm . KEY WORDS low carbon steel;oxide ;acicular ferrite ;hot diffusion ;microstructure · 360 · 北 京 科 技 大 学 学 报 2006 年第 4 期