Determining Johnson-Cook Constitutive Equation for Low-Carbon Steel via Taylor Anvil Test.

Lenka Kunčická,Radim Kocich,Miroslav Jopek,Karel Dvořák

doi:10.3390/ma14174821

Abstract

Tristal steel is low-carbon construction-type steel widely used in the automotive industry, e.g., for braking components. Given the contemporary demands on the high-volume production of such components, these are typically fabricated using automatic sequential machines, which can produce components at strain rates up to 103 s−1. For this reason, characterising the behaviour of the used material at high strain rates is of the utmost importance for successful industrial production. This study focuses on the characterisation of the behaviour of low-carbon steel via developing its material model using the Johnson-Cook constitutive equation. At first, the Taylor anvil test is performed. Subsequently, the acquired data together with the results of observations of structures and properties of the tested specimens are used to fill the necessary parameters into the equation. Finally, the developed equation is used to numerically simulate the Taylor anvil test and the predicted data is correlated with the experimentally acquired one. The results showed a satisfactory correlation of the experimental and predicted data; the deformed specimen region featured increased occurrence of dislocations, as well as higher hardness (its original value of 88 HV increased to more than 200 HV after testing), which corresponded to the predicted distributions of effective imposed strain and compressive stress.

Highlights

Published: 25 August 2021The primary focus in the field of bulk-forming in the automotive industry is on enhancing the performance of processing technologies and their optimisation towards higher speeds and increased productivity
Processes of plastic forming characterised by dynamic plastic deformations at high strain rates from 102 s−1 to 106 s−1, such as high-speed forming, impact hydroforming, pneumo-mechanical forming, electromagnetic forming, etc., have become very popular [8,9,10,11,12]
The primary analyses of the TRISTAL steel specimens were focused on the observations of their structures

Summary

Introduction

The primary focus in the field of bulk-forming in the automotive industry is on enhancing the performance of processing technologies and their optimisation towards higher speeds and increased productivity. High-speed forming has been a widely used room-temperature plastic deformation technology for manufacturing thin-walled and complex-shaped components [2,3,4], as well as for the production of modern types of materials, such as laminates, composites, and hybrid materials [5,6,7]. Processes of plastic forming characterised by dynamic plastic deformations at (ultra) high strain rates from 102 s−1 to 106 s−1 , such as high-speed forming (e.g., rotary swaging), impact hydroforming, pneumo-mechanical forming, electromagnetic forming, etc., have become very popular [8,9,10,11,12]. High-speed deformation is the basis of numerous tests investigating the performance of manufactured components (explosive and ballistic testing, armour crashworthiness tests, etc.)

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Conclusion