低碳钢超细晶铁素体的形成  

Formation of ultrafine ferrite in low-carbon steels

作　　者：崔文芳[1] 刘春明[1] 吴江华[1] 

机构地区：[1]东北大学材料与冶金学院辽宁省金属材料微结构设计与控制重点实验室,沈阳110004

出　　处：《材料研究学报》2006年第3期240-244,共5页Chinese Journal of Materials Research

基　　金：国家重点基础研究发展规划G1998061509资助项目.

摘　　要：将含碳量(质量分数)为0．057％和0．18％的低碳钢在不同过冷度、变形温度、变形速率和变形量的条件下进行热模拟实验,研究了含碳量和热变形条件对超细晶粒形成的影响．结果表明,变形前快速冷却(20℃／s)至Ar3以上附近温度并进行超过50％变形量的变形,能强烈促进过冷奥氏体形变诱发铁素体相变,铁素体在奥氏体(?)内平行的变形带上形核,并发生动态回复和再结晶,从而使组织细化．形变诱发的相变过程由碳的扩散所控制,当钢的含碳量比较高时,小过冷度、大变形量和中等变形速率有利于铁素体相变,晶界碳化物的析出能够抑制铁素体晶粒的长大,因而高碳含量钢表现出更好的细化晶粒效果．The thermal simulation tests for low-carbon steels with 0.057%C and 0.18%C were carried out in the conditions including undercooling, deformation temperature, deformation rate and deformation reduction to investigate the effect of carbon content and deformation conditions on the formation of the ultrafine ferrite grain in low-carbon steels and analysis the mechanism of refining grain. The results showed that undercooling before deformation and deformation more than 50% can promote transformation of austenite. The ferrite nucleates at the parallel deformation bands in austenite grains, and the subsequent dynamic recovery and recrystallization process occur in the interior of ferrite grains, resulting in ultrafine ferrite grains. The diffusion of carbon atoms in the steel dorminates the strain-induced transformation process. For the steel of higher carbon content, the small undercooling degree and medium deformation rate are beneficial to the short-distance diffusion of carbon atoms and ferrite transformation. In addition, the carbides precipitated on the grain boundaries can restrain the coarsening of ferrite grains. The finer grains can be obtained in the steel with higher carbon content.

关 键 词：金属材料 低碳钢 超细晶粒 含碳量 

分 类 号：TG142[一般工业技术—材料科学与工程]