Nucleation and Grain Boundary Evolution in Dynamic Recrystallization of 316LN Steel During Hot Deformation

Jiachen Liu,Huiqin Chen

doi:10.3389/fmats.2019.00209

Jiachen Liu, Huiqin Chen

Open Access

https://doi.org/10.3389/fmats.2019.00209

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Abstract

In this work, dynamic recrystallization (DRX) behavior of 316LN austenitic stainless steel was studied by hot compression experiments at temperature range of 900~1200℃ and strain rate range of 0.005~0.5 s−1. The Arrhenius hyperbolic sine function was given to fit well with the hot deformation flow behavior of 316LN steel and the average activation energy (Q) was obtained. The variation of DRX fraction and average grain size was studied and modeled. Microstructural evolution of 316LN steel during hot deformation in condition of 1100℃ and 0.05s-1 was studied by EBSD analysis. It was found that twining plays a significant role in nucleation and growth of DRX during hot deformation. The nucleation of DRX in 316LN steel was characterized by bulging of serrated grain boundaries. Twining took place near the serrated grain boundary in large amount, accelerating the separation of bulging from deformed parent grains to form DRX nucleus. At the steady state strain, uniformly refined DRX grains almost took charge of the microstructure of 316LN steel.

Highlights

IntroductionThe research of 316LN steel mainly focuses on two aspects: performance and hot deformation (Anita et al, 2006; Kim et al, 2009; Schwartz et al, 2010; Kim, 2012; Mathew et al, 2012; Samantaraya et al, 2012; Duan and Liu, 2013; Zhang et al, 2013; Chen et al, 2014; Samantaray et al, 2014; Sun et al, 2016)
316LN austenitic stainless steel has been chosen to manufacture heavy key structural components in nuclear power plant owing to its excellent corrosion resistance, high temperature mechanical properties, and adequate weldability (Jones, 1996; Zhang et al, 2014)
In terms of hot deformation, Duan and Liu (2013) and Zhang et al (2013) conducted researches on cracking issue of 316LN steel during hot deformation, and presented prediction models for cracking, respectively; Chen et al (2014) predicted the microstructural evolution of 316LN steel using cellular automaton method; Hot processing map of 316LN steel was built by Sun et al (2016) who discussed the hot workability of 316LN steel; Samantaraya et al (2012), Samantaray et al (2014) revealed the unbalance phenomenon between energy input and energy dissipation during hot deformation of 316LN steel

Summary

Introduction

The research of 316LN steel mainly focuses on two aspects: performance and hot deformation (Anita et al, 2006; Kim et al, 2009; Schwartz et al, 2010; Kim, 2012; Mathew et al, 2012; Samantaraya et al, 2012; Duan and Liu, 2013; Zhang et al, 2013; Chen et al, 2014; Samantaray et al, 2014; Sun et al, 2016). Grain refinement during primary deformation processing route is a challenge for manufacturing these heavy key structural components

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