Determination of processing maps for the warm working of vanadium microalloyed eutectoid steels

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• 作者：H. Rastegari^a ; ^b ; ^{rastegary@birjandut.ac.ir" class="auth_mail" title="E-mail the corresponding author} ; A. Kermanpur^b ; A. Najafizadeh^c ; M.C. Somani^d ; D.A. Porter^d ; E. Ghassemali^e ; A.E.W. Jarfors^e
• 关键词：Vanadium ; Eutectoid steel ; Dynamic spheroidization ; Processing maps
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：21 March 2016
• 年：2016
• 卷：658
• 期：Complete
• 页码：167-175
• 全文大小：5273 K

文摘

Microalloying of an eutectoid steel with V may facilitate formation of dispersed nano-scaled VC particles in the microstructure during thermomechanical processing or subsequent heat treatment. In this research, the constitutive flow behavior of vanadium microalloyed eutectoid steel has been investigated in the temperature range 620–770 °C at strain rates in the range 0.01–10 s⁻¹. Microstructural characterization of the deformed specimens was conducted using SEM and EBSD techniques. In this context, various deformation mechanisms occurring during warm deformation have been characterized and delineated through construction of a processing map by establishing a power dissipation map and an instability map for the steel and superimposing them. The results show that the pearlitic microstructure exhibits several deformation mechanisms within these warm working conditions. Dynamic spheroidization of cementite lamella takes place in the range 660–720 °C and 0.01–0.1 s⁻¹ with a power dissipation efficiency of 27–33%, characterizing a safe window of processing this steel. The presence of vanadium carbides at grain boundaries strengthened the pearlitic microstructure and retarded the occurrence of some deformation defects during low temperature, high speed deformation in the range 620–720 °C and 1–10 s⁻¹.