Constitutive relationship and hot deformation behavior of Armco-type pure iron for a wide range of temperature. (January 2015)

• Record Type: Journal Article
• Authors: Fan, Q.C.; Jiang, X.Q.; Zhou, Z.H.; Ji, W.; Cao, H.Q.
• Is Part Of: Materials & design. Volume 65(2015:Jan.)
• Page Start: 193
• Page End: 203
• Publication Date: 2015-01
• Subjects: Pure iron -- Constitutive equation -- Predictability -- Dynamic recrystallization -- Flow stress -- Hot deformation; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2014.08.074
• Languages: English
• ISSNs: 0264-1275

Abstract

Highlights: Hot deformation behavior of Armco-type pure iron has been analyzed. γ-Fe and α-Fe undergo completed dDRX and uncompleted dDRX, respectively. Sharp increase in peak stress appears as long as α-Fe changes to γ-Fe. Modified constitutive equation is used to predict the flow stress of γ-Fe and α-Fe. Predictability of the constitutive equation is evaluated in terms of the R, RSME, and AARE. Abstract: The hot deformation behavior and constitutive relationship of Armco-type pure iron were investigated using isothermal compression tests with a wide range of temperature and strain rate ranging from 923 to 1523 K, and 0.1 to 10 s −1, respectively. When deformed with a single phase, the flow stress of Armco-type pure iron increases accompanied by the increase of strain rate and the decrease of deformation temperature. Instability phenomenon of Armco-type pure iron appears when deformed with dual phase. γ-Fe undergoes completed discontinuous dynamic recrystallization (dDRX) at all hot deformation conditions. α-Fe undergoes uncompleted dDRX process at high temperature and low strain rate, however, dynamic recovery (DRV) process is the main restoration process for α-Fe at low temperature and high strain rate. The modified Arrhenius-type constitutive equation considering strain compensation is used to describe the flow stress of γ-Fe and α-Fe. From correlation coefficient ( R ), root mean square error (RMSE) and average absolute relative error (AARE), the predictability of the constitutive equation for the two phases of Armco-type pure iron was evaluated.