The Effect of Preliminary Thermomechanical Processing on the Kinetics of Localized Plasticity Autowaves in Trip Steel

Dina V Orlova,Vladimir I Danilov,Galina V Shlyakhova,Lidiya V Danilova,Lev B Zuev,Vadim V Gorbatenko

doi:10.3390/met10111494

Abstract

The kinetics of the martensitic transformation fronts in transformation-induced plasticity (TRIP) steel was studied in relation to preliminary thermomechanical treatment using the digital image correlation method. It was found that warm rolling of steel to 40–63% reduction significantly increases the stress of the onset of strain-induced phase transformation and changes the loading curve stages. The strain-induced phase transformation in TRIP steel occurring through the formation of Lüders and Portevin–Le Chatelier bands is shown to be an autowave process of localized plasticity. The austenite → martensite transformation at the elastic-plastic transition occurs in the form of several switching localized plasticity autowaves. At the jerky flow stage, excitation autowaves of localized plasticity are generated and propagate repeatedly until the strain-induced austenite → martensite transformation is completed. It is shown for the first time that the sources of excitation autowaves in the material are the sites of nucleation or annihilation of switching autowaves.

Highlights

Strain-induced thermoelastic martensitic transformations have been the subject of numerous experimental and theoretical investigations [1,2,3,4,5]
ItItis argued in thein literature that the martensitic-type strain-inducedstrain-induced phase transformation is argued the literature that the martensitic-type phase oftransformation metastable austenite in a medium manganese steel is manifested through the formation of Lüders band (LB) of metastable austenite in a medium manganese transformation-induced plasticity (TRIP) steel is manifested through the onformation the yield of plateau uneven deformation
The findings of this study into the structure and behavior of plastic strain macrolocalization in metastable austenitic-martensitic steel depending on its preliminary thermomechanical processing yielded the following conclusions: 1

Summary

Introduction

Strain-induced thermoelastic martensitic transformations have been the subject of numerous experimental and theoretical investigations [1,2,3,4,5]. This specific mechanism determines the properties of the material such as increased strength, superelasticity, shape memory effect and others. The transformation can occur with the formation of ε-martensite, which is an intermediate phase with an hexagonal close-packed lattice, HCP lattice. The use of high-resolution techniques helped to determine the microscopic mechanisms of the main types of transformations, such as γ → α0 , γ → ε, γ → ε → α0 , in deformed metastable austenitic steels [1,3,7,8,9]

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