新型奥氏体耐热钢CHDG-A的动态再结晶行为及其动力学模型  

Dynamic Recrystallization Behavior and Kinetics Model of a New Developed Austenitic Heat Resistant Steel CHDG-A

作　　者：程晓农[1] 桂香 罗锐[1] 徐桂芳[1] 袁志钟[1] 周宇森 高佩[1,2] CHENG Xiaonong;GUI Xiang;LUO Rui;XU Guifang;YUAN Zhizhong;ZHOU Yuseng;GAO Pei(School of Materials Science and Engineering,Jiangsu University,Zhenjiang 212013,China;Jiangsu Yinhuan Precision Steel Tube Co.,Ltd.,Yixing 214203,China)

机构地区：[1]江苏大学材料科学与工程学院,镇江212013 [2]江苏银环精密钢管有限公司,宜兴214203

出　　处：《材料研究学报》2020年第8期611-620,共10页Chinese Journal of Materials Research

基　　金：江苏省高等学校自然科学研究面上项目(19KJB430001);江苏省重点研发计划(BE2017127)。

摘　　要：进行新型奥氏体耐热钢(CHDG-A)的热压缩实验,研究了在900~1100℃、应变速率为0.01-10 s-1条件下这种钢的热变形特征。结果表明:随着变形温度的提高或应变速率的降低这种钢的流变应力显著降低。基于Arrhenius模型构建了这种材料的本构方程,得到CHDG-A热变形激活能Q为515.618 kJ/mol。微观组织分析结果表明,动态再结晶(DRX)是该材料在实验热变形条件下最主要的软化方式,DRX形核主要通过晶界弓出,变形温度的升高和应变速率降低均有利于再结晶形核。基于真应力-应变曲线求得动态再结晶用Z参数表示的峰值和临界值(σp、εp、σc和εc),并确定了εc/εp,σc/σp的比值分别为0.52和0.98。同时,还基于Avrami方程建立了CHDG-A的DRX动力学模型。The deformation behavior and microstructural evolution of a new developed austenitic heat resistant steel CHDG-A were investigated by hot compression tests with strain rate in the range of 0.01-10 s-1 at 900~1100℃.The results show that either increasing the deformation temperature or decreasing the strain rate,the flow stress level reduces remarkably.Accurate constitutive equations were established between peak stress and deformation parameters,i.e.,temperature and strain rate by the regression analysis of sine hyperbolic function.The hot deformation activation energy of CHDG-A was calculated to be 515.618 kJ/mol.From the deformed microstructures it is found that dynamic recrystallization(DRX)is the principal softening mechanism during hot working.The DRX process may initiate from nucleus formed at bulging out of grain-boundaries,which can be promoted by the increase of temperature and the decrease of strain rate.The values of peak stress,critical stress,peak strain and critical strain for DRX were determined from the true strain-true stress curves and their equations related to the Zener-Hollomon parameter were obtained.The critical strain and corresponding stress for DRX can be expressed through the parameter Z.The critical ratios ofεc/εp andσc/σp are also identified,which are 0.52 and 0.98,respectively.Moreover,the DRX kinetics for CHDG-A can be represented in the form of Avrami equation,and the predicted volume fraction of new grains based on the developed model agrees well with the experimental results.

关 键 词：金属材料 奥氏体耐热钢 热变形 Z参数 动态再结晶 

分 类 号：TG142.71[一般工业技术—材料科学与工程]