摘要
通过热模拟实验研究了不同形变温度及在700℃下不同形变量时中碳钢35K的组织演变过程。结果表明,中碳钢通过形变可获得形变诱导铁素体(DIF);形变提高奥氏体向铁素体转变温度,随着形变温度的降低,DIF含量呈反“S”形增加,即先缓慢增加,随后快速增加,当DIF量超过平衡态铁素体量时,其增加趋势趋缓。随700℃形变量的增加,DIF含量呈“S”形增加,在形变量为0.7时可获得良好的球化组织。在中碳钢形变后的控冷过程中,根据形变量和形变温度所影响的未转变的奥氏体尺寸、形变储能、富碳程度和能量与成分起伏等,未转变的奥氏体将发生不同于传统未变形奥氏体的转变。因此,控制轧制和控制冷却后可获得离异珠光体、球粒状或短棒状渗碳体的微观组织。
Hot compression tests at different deformation temperatures and with different amount of deformation at 700°C are carried out to study the microstructure evolution of medium carbon steel 35K. The results show that deformation induced ferrite (DIF) can be obtained through suitable deformation for medium carbon steel as deformation raises the transformation temperature from austenite to ferrite. The curve of the volume fraction of DIF via deformation temperatures looks like a mirror shape of S, that is to say, with the decreasing of deformation temperature, the volume fraction of DIF increases slowly firstly and then quickly, when the volume fraction of DIF exceeds the equilibrium content, its increasing will slow down. The curve for the volume fraction of DIF via different amount of deformation at 700°C looks like a S shape. A rather good spheroidized microstructure can be obtained after controlled cooling when deformed at 700°C for Ε=0.7. The decomposition of untransformed austenite during controlled cooling differs from that of conventional non-deformed austenite according to the sizes of untransformed austenite, deformation stored energy, the degree of carbon concentration, the fluctuation of energy or component which are influenced by the deformation temperature and the amount of deformation strain. Therefore, degenerated pearlite and/or spherical or rod-like cementite can be obtained after controlled rolling and controlled cooling.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2005年第4期69-73,共5页
Transactions of Materials and Heat Treatment
基金
国家高技术发展计划资助项目(2003AA331030)
关键词
中碳钢
热模拟
组织演变
形变诱导铁素体
Austenite
Dynamics
Ferrite
Microstructure
Pearlite
Phase transitions
Rolling
