锻压技术

超高强度钢扩散型相变测试及其动力学模型

英文标题：Diffusion phase transformation test of ultra high strength steel and its kinetic model

单位：重庆大学

分类号：TG131

出版年,卷(期):页码：2018,43(8):178-183

摘要：

基于Gleeble 3500热模拟试验机开展了一系列BR1500HS钢圆棒试样的等温相变测试，得到了其扩散型相变的热膨胀曲线，结合试样微观组织观察结果综合确立扩散型相的种类，进而绘制出BR1500HS钢扩散型相变的等温转变曲线（TTT曲线），曲线呈“双C型”，“鼻温”分别为480 和640 ℃，这两个温度下对应孕育期最短。最后，引入Johnson-Avrami动力学方程建立了该材料扩散型相变动力学模型，所建立的模型可以预测超高强度钢扩散型相变温度区间内任一转变条件下扩散型相转变体积分数与时间的关系：针对转变温度而言，在较低温度下转变速率快；针对转变阶段而言，在转变中间阶段转变速率快，具体定量关系由模型表达式给出。

The experiments of isothermal phase transformation for a series of steel BR1500HS round bar samples were conducted by thermal simulated test machine Gleeble 3500, and the thermal expansion curves of diffusion phase transformation were obtained. Combined with the observation results of sample microstructure, the species of diffusion phase were ascertained, and the time-temperature-transformation(TTT) curves of diffusion phase transformation of steel BR1500HS were drawn. Moreover, the TTT curves presente as ‘double C’ type, and the ‘nose temperatures’ are 480 and 640 ℃ respectively which exhibite the shortest incubation stage. In the end, the diffusion phase transformation kinetics model was established by introducing the Johnson-Avrami kinetics equation, which could predict the relationship between transformed volume fraction and time in the complete diffusion transformation temperature region of UHSS under any transition conditions. Thus, for transformation temperature, the transition velocity is fast at lower temperature, and for transformation stage, the transition velocity is fast at the middle stage. Finally, the specific quantitative relationship was given by the expressions in the model.

基金项目：

重庆大学大学生科研训练计划项目(CQU-SRTP-2017166;CQU-SRTP-2017162;CQU-SRTP-2016132)

张谦（1998-），男，本科，E-mail：1137691086@qq.com；通讯作者：权国政（1980-），男，博士，副教授，E-mail：quangz3000@sina.com

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