The Use of Acoustic Emission and Neural Network in the Study of Phase Transformation below MS.

Małgorzata Łazarska,Andrzej Trafarski,Zbigniew Ranachowski,Tadeusz Z Wozniak,Szymon Marciniak

doi:10.3390/ma14030551

Abstract

Acoustic emission and dilatometry were applied to investigate the characteristics of phase transformations in bearing steel 100CrMnSi6-4 during austempering below the martensite start temperature (MS 175 °C) at 150 °C. The aim of this study is to characterize the product of transformation occurring below the MS temperature using various research methods. Analysis of the dilatometric curves shows that, after the formation of athermal martensite below the MS temperature, the austenite continues to undergo isothermal transformation, indicating the formation of bainite. Additionally, tests were carried out with the use of acoustic emission during isothermal hardening of the adopted steel. The obtained acoustic emission signals were analyzed using an artificial neural network. The results, in the form of a graph of the frequency of acoustic emission (AE) event occurrence as a function of time, make it possible to infer about the bainite isothermal transformation. The results of this research may be used in the future to design optimal heat treatment methods and, consequently, may enable desired microstructure shaping.

Highlights

Great technological progress in recent times has caused demands concerning used materials to continue increasing
The MS temperature determined on the basis of the dilatometric tests was Dilatometric tests were made to investigate the transformations of austenite und thermal conditions below the determined MS temperature
Dilatometric investigatethe thetransformations transformationsofofaustenite austenite under isoDilatometrictests testswere were made to investigate under isothermal conditions below the results are areshown showninin thermal conditions below thedetermined determinedMM

Summary

Introduction

Great technological progress in recent times has caused demands concerning used materials to continue increasing. Contemporary materials science, materials engineering, and structural metallurgy tend towards the manufacture of materials that meet the requirements of more and more challenging tasks of different industrial sectors. One of the methods that may be used to considerably improve the quality of metals is heat treatment. The first research on the effects occurring during austenite decomposition at a constant temperature was done for eutectoid steel by E.

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