耐热合金热压缩修正后本构方程及热加工图
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摘要
通过热模拟压缩实验研究了耐热合金CN617在变形温度为950~1 150℃、应变速率为0.01~10s-1条件下的热变形行为,修正了实验中由于摩擦和变形热效应引起的流变应力误差,并采用修正后的流变应力值,通过回归分析建立了CN617合金的热变形本构方程并绘制了热加工图。计算得出锻态耐热合金CN617热变形的热激活能平均为550kJ/mol。利用热加工图确定了CN617合金热变形时流变失稳区,分析得到了CN617合金流变失稳的原因是极少动态再结晶发生以及局部绝热变形带的形成。
The hot deformation behavior of the forged heat-resistant alloy CN 617 were analyzed at 950-1 150℃,in strain rate range of 0.01-10s-1 by the compression tests,the errors in flow stress caused by friction and thermal effect were corrected.Constitutive equation of alloy CN617 at high temperature is established by curvilinear regression method and processing map is developed on the basis of the corrected flow stress values.The average apparent activation energy for hot working is calculated to be 550kJ/mol.The instability regime of CN617 alloy is confirmed using the processing maps,the reason of that is less of the incomplete dynamic recrystallization and the formation of localized adiabatic shear bands.
The hot deformation behavior of the forged heat-resistant alloy CN 617 were analyzed at 950-1 150℃,in strain rate range of 0.01-10s-1 by the compression tests,the errors in flow stress caused by friction and thermal effect were corrected.Constitutive equation of alloy CN617 at high temperature is established by curvilinear regression method and processing map is developed on the basis of the corrected flow stress values.The average apparent activation energy for hot working is calculated to be 550kJ/mol.The instability regime of CN617 alloy is confirmed using the processing maps,the reason of that is less of the incomplete dynamic recrystallization and the formation of localized adiabatic shear bands.
引文
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[2]Viswanathan R,Henry J F,Tanzosh J,et al.U.S.Program on materials technology for ultra-supercritical coal power plants[J].Journal of Materials Engineering and Performance,2005,14(3):281.
[3]Goetz R L,Semiatin S L.The adiabatic correction factor for deformation heating during the uniaxial compression test[J].Journal of Materials Engineering and Performance,2001,10(6):710.
[4]Ebrahimi R,Najafizadeh A.A new method for evaluation of friction in bulk metal forming[J].Journal of Materials Processing Technology,2004,152(2):136.
[5]张伟红,张士宏.NiTi合金热压缩实验数据的修正及其本构方程[J].金属学报,2006,42(10):1036.
[6]Liang X P,Liu Y,Li H Z,et al.Constitutive relationship for high temperature deformation of powder metallurgy Ti-47Al-2Cr-2Nb-0.2Walloy[J].Material and Design,2012,37:40.
[7]牛济泰.材料和热加工领域的物理模拟技术[M].北京:冶金工业出版社,1999.
[8]Jonas J J,Sellars C M,Tegart W J M.Strength and structure under hot-working conditions[J].International Materials Reviews,1969,14(14):1.
[9]Sellar C M,Tegart W J M.On the mechanism of hot deformation[J].Acta Metallergica,1966,14:1136.
[10]Pasad Y V R K.Processing maps:a status report[J].Journal of Materials Engineering and Performance,2003,12(6):638.
[11]乔慧娟,李付国,冀国良,等.Aermet 100钢高温变形行为及热加工图研究[J].稀有金属材料与工程,2014,43(4):926.