Analysis of deformation behavior and workability of advanced 9Cr-Nb-V ferritic heat resistant steels

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:604

Article

Zhang, Wen Feng^1,2,3  Sha, Wei⁴  Yan, Wei²  Wang, Wei²  Shan, Yi Yin²  Yang, Ke² 

[1] Univ Sci & Technol China, Hefei 230026, Peoples R China

[2] Chinese Acad Sci, Inst Met Res, Shenyang 110016, Peoples R China

[3] Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China

[4] Queens Univ Belfast, Sch Planning Architecture & Civil Engn, Belfast BT9 5AG, Antrim, North Ireland

关键词: Steel;    Mechanical characterization;    Martensite;    Thermomechanical processing;    Recrystallization;    Phase transformation;   

DOI  :  10.1016/j.msea.2014.02.050

来源: Elsevier

【 摘 要 】

Hot compression tests were carried out on 9Cr-Nb-V heat resistant steels in the temperature range of 600-1200 degrees C and the strain rate range of 10(-2)-10(0) s(-1) to study their deformation characteristics. The full recrystallization temperature and the carbon-free bainite phase transformation temperature were determined by the slope-change points in the curve of mean flow stress versus the inverse of temperature. The parameters of the constitutive equation for the experimental steels were calculated, including the stress exponent and the activation energy. The lower carbon content in steel would increase the fraction of precipitates by increasing the volume of dynamic strain-induced (DSIT) ferrite during deformation. The In(e) versus In(Z) and the ln(sigma(c)) versus In(Z) plots for both steels have similar trends. The efficiency of power dissipation maps with instability maps merged together show excellent workability from the strain of 0.05 to 0.6. The microstructure of the experimental steels was fully recrystallized upon deformation at low Z value owing to the dynamic recrystallization (DRX), and exhibited a necklace structure under the condition of 1050 degrees C/0.1 s(-1) due to the suppression of the secondary flow of DRX. However, there were barely any DRX grains but elongated pancake grains under the condition of 1000 degrees C/1 s(-1) because of the suppression of the metadynamic recrystallization (MDRX). (C) 2014 Elsevier B.V. All rights reserved.

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