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Multibranches of acoustic emission as identifier for deformation mechanisms in additively manufactured 316L stainless steel

Accepted version
Peer-reviewed

Type

Article

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Abstract

2 Abstract The multiple collapse mechanisms of complex materials produced by additive manufacturing (AM) were identified by measurements of the acoustic emission (AE) of the samples under tension. A perfect correlation between AE avalanches and deformation mechanisms is shown to hold in the extremely complex AM metallic materials such as ‘as-built’ and ‘stress-relieved’ AM 316L stainless steel (SS). The main criterion is that multibranches of the energy-amplitude scaling in AE proves the coexistence of several deformation mechanisms. The as-built AM 316L SS shows three branches in the energy- amplitude scaling of AE signals, which originate from dislocation movements, twinning-detwinning processes and stress-induced martensitic transformations. After stress-relieving annealing at 600°C for 1 h, two branches remain visible with the dominant deformation mechanisms of dislocation movement and twinning-detwinning. The energy exponent of dislocation avalanches is  =1.6, which is not affected by the heat treatment. The twinning-detwinning exponent increases from 1.8 to 2.0 after annealing. The avalanche behavior of the martensitic transformation shows power laws with energy exponents near  =1.65 in stress-induced martensite in as-built AM 316L SS and  =1.8 for strain- induced martensite in stress-relieved AM 316L SS. This multibranching phenomenon can, thus, be used to identify the mechanisms underlying the deformation of AM-alloys and facilitates online monitoring of deformation processes

Description

Keywords

40 Engineering, 4016 Materials Engineering

Journal Title

Additive Manufacturing

Conference Name

Journal ISSN

2214-8604
2214-8604

Volume Title

Publisher

Elsevier BV
Sponsorship
Engineering and Physical Sciences Research Council (EP/P024904/1)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (861153)