摘要
采用热模拟试验机在300~850℃施加20%的压缩预变形后进行300℃等温相变实验,研究了预变形温度对中碳纳米贝氏体钢等温相变动力学及组织的影响。结果表明,预变形工艺使贝氏体相变孕育期显著缩短;低温预变形工艺使贝氏体相变在整个等温区间内均得到加速,高温预变形工艺使贝氏体相变仅在等温初期得到加速,等温后期相变速率明显减缓;随预变形温度的降低,贝氏体铁素体板条厚度逐渐增加;预变形工艺增加了贝氏体相变组织小角度晶界的频率,低温预变形试样的小角度晶界频率高于高温预变形试样。利用解析相变模型计算了贝氏体等温相变过程中的相变动力学参数n,并对贝氏体相变过程中的形核长大方式进行了判定,发现预变形工艺改变了贝氏体相变的形核位置,低温预变形试样主要以晶隅形核为主,高温预变形试样主要以晶棱、晶面形核为主。
As a new steel, nanobainite steel has favourable strength and good plasticity, but the bainite transformation needs a longer time, so as to severely slow production efficiency down. So, the research of acceleration methods of bainite transformation is of significance. In this work, in order to accelerate the bainite transformation rate, the 20% compression pre-deformation at 300~850 ℃ and isothermal transformation at 300 ℃ were conducted on a thermal simulator. The effects of pre-deformation temperature on nanobainite transformation kinetics and microstructure of the medium carbon nanobainite steel were investigated. The results showed that pre-deformation process obviously shortened the incubation time of bainite transformation. Low pre-deformation temperature could accelerate bainite transformation at whole isothermal region, while high pre-deformation temperature accelerated bainite transformation at the initial stage, and hindered bainite transformation at later stage. Bainite ferrite lath thickness was increased with decreasing pre-deformation temperature. The pre-deformation process increased the frequency of small angle grain boundary of bainite transformation microstructure, and the frequency of small angle grain boundary of low pre-deformation temperature was higher than that of high pre-deformation temperature. The kinetic parameters n of bainite transformation was calculated by the analytical model, the model of nucleation and growth were identified, the pre-deformation process changed the nucleation position of bainite transformation. The crystal corner nucleation was mainly obtained through low pre-deformation temperature, and the crystal edge and the crystal face nucleation were mainly obtained through high pre-deformation temperature.
作者
徐士新
余伟
李舒笳
王坤
孙齐松
XU Shixin;YU Wei;LI Shujia;WANG Kun;SUN Qisong(Research Institute of Technology,Shougang Group Co.,Ltd.,Beijing 100043,China;Engineering Research Institute,University of Science and Technology Beijing,Beijing 100083,China;Beijing Key Laboratory of Green Recyclable Process for Iron and Steel Production,Shougang Group Co.,Ltd.,Beijing 100043,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第8期1113-1121,共9页
Acta Metallurgica Sinica
基金
"十二五"国家科技支撑计划项目No.2012BAE03B01~~
关键词
预变形温度
纳米贝氏体
相变动力学
显微组织
解析模型
pre-deformation temperature
nanobainite
transformation kinetics
microstructure
analytical model
