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Strain energy method to determine static recrystallization volume fraction of microalloyed steel Baochun Zhao1,2 · Lei Huang1,2 · Huixia Ma1,2 · Wenjie Zhen1,2 Received: 15 July 2020 / Accepted: 3 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Double compression method is an effective method to determine static recrystallization volume fraction of materials because there is a marked difference in flow stress between two passes, which is caused by static recrystallization. And now offset method that is based on some specific flow stress is widely used. However, this method is not suitable to determine static recrystallization volume fraction for all the materials, especially for those alloyed steels. As the measurement of yield or flow stress is not very sensitive to a subtle change in precipitation, strain energy is the integration of the flow stress and so it is more sensitive to the subtle change and so this method could be better. This study aims to present strain energy method to determine static recrystallization volume fraction in details by performing uniaxial compression test on a microalloyed steel. And it was found that there were two points worth to note while performing this method: one is that if work hardening plays a dominant role during compression process, static recrystallization volume fraction can be determined by analyzing double compression curve and its extrapolation, on the contrary if dynamic softening plays the dominant role, the static recrystallization volume fraction has to be determined with the assistance of curve from single pass compression test. Keywords  Static recrystallization · Strain energy method · Flow stress · Uniaxial compression

1 Introduction During hot working process, static recovery or recrystallization may occur in the material in the pass interval [1, 2], which has a great impact on the quality of the final products [3, 4]. Therefore, it is of great importance to study the static recrystallization behavior of materials in the pass interval and it is also a basic work for microstructure prediction. So in recent decades, significant effort has been put into establishing the models for static recrystallization [1, 5–7]. At present, there are many methods to determine static recrystallization volume fraction (SRD), and offset method is commonly regarded as a convenient way [8–11]. Although this method is suitable to calculate SRD for many steels, it is based on some specific stress, which is not very sensitive to a subtle change in precipitation. Therefore, there should be * Baochun Zhao [email protected] 1



Key Laboratory of Metal Materials for Marine Equipment and Application, Anshan 114009, Liaoning, China



Iron and Steel Research Institute of AnGang Group, Anshan 114009, Liaoning, China

2

another method to determine SRD for alloyed steels where some particles precipitate in the pass interval. As the precipitated particles are concerned, strain energy is the integration of flow stress, which is more sensitive to the chang