Shear band patterning and post-critical behavior in AISI 4340 steel with different microstructure

Navarro, Pedro Franco; Chiu, Po-Hsun; Higgins, Andrew; Serge, Matthew; Nesterenko, V. F.

doi:10.1016/j.ijimpeng.2017.10.011

“…In this regard, and in the context of direct in situ observational studies, high-rate deformation configurations such as punching and cutting, which effect nucleation of a single, well-defined shear band at an a priori known location, should prove most useful. The simultaneous initiation of shear bands at multiple nucleation sites and their mutual interactions, such as in explosively loaded thick-walled cylinders [146][147][148], is an even more involved problem that is largely outside the range of the present review.…”

Section: Summary and Concluding Remarksmentioning

confidence: 96%

Shear Bands in Materials Processing: Understanding the Mechanics of Flow Localization From Zener's Time to the Present

Viswanathan

¹

,

Yadav

²

,

Sagapuram

³

2020

Applied Mechanics Reviews

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Shear banding is a material instability in large strain plastic deformation of solids, where otherwise homogeneous flow becomes localized in narrow micrometer-scale bands. Shear bands have broad implications for materials processing and failure under dynamic loading in a wide variety of material systems ranging from metals to rocks. This year marks 75 years since the publication of Zener and Hollomon's pioneering work on shear bands (Zener and Hollomon, J Appl. Phys., 15, 22–32, 1944), which is widely credited with drawing the attention of the mechanics community to shear bands and related localization phenomena. Since this landmark publication, there has been significant experimental and theoretical investigation into the onset of shear banding. Yet, given the extremely small length and time scales associated with band development, several challenges persist in studying the evolution of single bands, postinitiation. For instance, spatiotemporal development of strain fields in the vicinity of a band, crucial to understanding the transition from localized flow to fracture, has remained largely unexplored. Recent full-field displacement measurements, coupled with numerical modeling, have only begun to ameliorate this problem. This article summarizes our present understanding of plastic flow dynamics around single shear bands and the subsequent transition to fracture, with special emphasis on the postinstability stage. These topics are covered specifically from a materials processing perspective. We begin with a semihistorical look at some of Zener's early ideas on shear bands and discuss recent advances in experimental methods for mapping localized flow during band formation, including direct in situ imaging as well as ex situ/postmortem analyses. Classical theories and analytical frameworks are revisited in the light of recently published experimental data. We show that shear bands exhibit a wealth of complex flow characteristics that bear striking resemblance to viscous fluid flows and related boundary layer phenomena. Finally, new material systems and strategies for reproducing shear band formation at low speeds are discussed. It is hoped that these will help further our understanding of shear band dynamics, the subsequent transition to fracture, and lead to practical “control” strategies for suppressing shear band-driven failures in processing applications.

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“…In this regard, and in the context of direct in situ observational studies, high-rate deformation configurations such as punching and cutting which effect nucleation of a single, well-defined shear band at an a priori known location should prove most useful. The simultaneous initiation of shear bands at multiple nucleation sites and their mutual interactions, such as in explosively loaded thick-walled cylinders [130][131][132], is an even more involved problem that is largely outside the range of the present review.…”

Section: Shear Band Control and Some Practical Applicationsmentioning

confidence: 96%

Shear bands in materials processing: Understanding the mechanics of flow localization from Zener's time to the present

Viswanathan,

Yadav,

Sagapuram

2020

Preprint

0

View full text Add to dashboard Cite

Shear banding is a material instability in large strain plastic deformation of solids, where otherwise homogeneous flow becomes localized in narrow micrometer-scale bands. Shear bands have broad implications for materials processing and failure under dynamic loading in a wide variety of material systems ranging from metals to rocks. This year marks nearly 75 years since the publication of Zener and Hollomon's pioneering work on shear bands (C. Zener and J. H. Hollomon, J Appl. Phys., 15:22-32, 1944) which is widely credited with drawing the attention of the mechanics community to shear bands and related localization phenomena. Since this landmark publication, there has been significant experimental and theoretical investigation into the onset of shear banding. Yet, given the extremely small length and time scales associated with band development, several challenges persist in studying the evolution of single bands, post-initiation. For instance, spatiotemporal development of strain fields in the vicinity of a band, crucial to understanding the transition from localized flow to fracture, has remained largely

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“…Sutter and List [15] conducted orthogonal cutting tests on a specific ballistic set-up to study the change in morphology and mechanism of chip formation of Ti6Al4V. More recently, Navarro et al [16] explored the pattern of multiple shear bands in AISI 4340 steel using the Thick-Walled Cylinder method.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Adiabatic Shear Bands in Orthogonal Machining of Ti6Al4V Using a Rigid-Viscoplastic Finite Element Analysis

Friderikos

¹

,

Sagris

²

,

David

³

et al. 2020

Metals

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Catastrophic shear instability is the dominant mechanism during orthogonal cutting of Ti6Al4V. Chip segmentation even at low speeds testifies to the emergence of some kind of instability during plastic deformation of the material. Among the theoretical models, catastrophic thermoplastic slip is proposed as a mechanism to explain the destabilization of homogeneous plastic deformation, which results in localized, band-like adiabatic shear deformation. On the other hand, fracture models which consider machining as a mechanism of ductile or brittle fracture are used to explain the segmented chip formation as a periodic crack generation mechanism. This work aims at elucidating the fundamental mechanisms of the above theoretical models using a coupled thermomechanical rigid-viscoplastic FEM analysis. Introducing an energy criterion for ductile damage, numerical results showed that failure within the adiabatic shear band (ASB) is a post-localization mechanism occurring after intense shear localization. Simulations revealed a void initiation and coalescence mechanism which resembles an array of discontinuous degraded elements of nearly ellipsoidal shapes that grows and progressively coalesces forming a macro crack inside the ASB. Several aspects of ASB formation are addressed, among others, the micro-scale spatial temperature profile, parametric studies of critical damage energies, chip segmentation frequency, etc. Experimental results of ASB formation pertaining to chip morphology and cutting forces are compiled and analyzed to evaluate the FEM model at the low speed regime.

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Shear band patterning and post-critical behavior in AISI 4340 steel with different microstructure

Cited by 15 publications

References 48 publications

Shear Bands in Materials Processing: Understanding the Mechanics of Flow Localization From Zener's Time to the Present

Shear Bands in Materials Processing: Understanding the Mechanics of Flow Localization From Zener's Time to the Present

Shear bands in materials processing: Understanding the mechanics of flow localization from Zener's time to the present

Simulation of Adiabatic Shear Bands in Orthogonal Machining of Ti6Al4V Using a Rigid-Viscoplastic Finite Element Analysis

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