贝氏体相变的形核与长大——贝氏体相变新机制(一)  

Nucleation and Growth of Bainite Phase Transformation——New Mechanism of Bainite Phase Transformation(1)

作　　者：刘宗昌[1] 计云萍[2] 任慧平[2] 

机构地区：[1]内蒙古科技大学分析测试中心,内蒙古包头014010 [2]内蒙古科技大学材料与冶金学院,内蒙古包头014010

出　　处：《热处理技术与装备》2017年第2期1-7,共7页Heat Treatment Technology and Equipment

基　　金：国家自然科学基金(51261018)

摘　　要：研究贝氏体形核长大具有重要理论价值。实验观察了贝氏体的形核,从块状贝氏体形成机理研究起,延伸到各种碳含量钢的贝氏体相变机制,指出在超低碳钢中是γ→BF相变,在其他钢中是贫碳区(γ)→BF相变,本质上相同,仅仅组织形貌不同。奥氏体中存在贫碳区,依靠涨落形成贫碳区,贝氏体铁素体在贫碳区中形核。形核地点优先选择奥氏体晶界,仅下贝氏体可在晶内形核。计算了临界晶核尺寸和形核功。贝氏体形核-长大是界面上原子非协同热激活跃迁过程。超低碳贝氏体可呈块状、条片状,增加碳含量时,则以亚单元方式形成贝氏体铁素体(BF),形貌从块状向条片状演化。It is of great significance in theory to study the nucleation and growth of bainite. The formation mechanism of massive bainite and bainite phase transformation in different carbon content steels are stud- ied. The results show that the transformation in ultra low-carbon steel is from γ to BF and that in other steels is from poor-carbide region γ to BF. They are same in essence, merely different in morphology. There are poor-carbide regions in austenite by fluctuation and the bainite ferrite can nucleate in the poor- carbide regions. The nucleation prioritizes in austenite grain boundary. Only the lower bainite can nucleate in the grain interior. The critical nucleus size and the nucleation energy were calculated. The nucleation and growth of hainite depend on the non-synergic thermal activation transition of the interracial atoms. The morphology of ultra low-carbon bainite can present in massive or lamella shape. With the increase of the carbon content, the bainite ferrite comes from the subunits and the morphology also evolves from massive shape to lamella shape.

关 键 词：贝氏体相变 形核 形核功 晶界 贫碳区 热激活跃迁 

分 类 号：TG142.1[一般工业技术—材料科学与工程]