Metallographic Etching of Aluminium and Its Alloys for Restoration of Obliterated Marks in Forensic Science Practice and Investigations

Kuppuswamy, Ramesh

doi:10.5772/15693

Cited by 12 publications

(14 citation statements)

References 28 publications

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“…This resulting deformation extends to some depth below the stamped mark and is known as the zone of plastic strain. [1][2][3][4][5][6] Although the shape of this underlying region will be complex depending on various factors, it can be considered as a sphere to make an estimate of the depth with its radius equating to the depth of the zone of plastic strain. 6 This area has physical and chemical properties that differ from those of non-stamped metal due to the changes in its microstructure.…”

Section: Introductionmentioning

confidence: 99%

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Restoration of defaced serial numbers using lock-in infrared thermography (Part I)

Unobe

Lau

Kalivas

et al. 2019

J. Spectral Imaging

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Infrared thermal imaging is an evolving approach useful in non-destructive evaluation of materials for industrial and research purposes. This study investigates the use of this method in combination with multivariate data analysis as an alternative to chemical etching; a destructive method currently used to recover defaced serial numbers stamped in metal. This process involves several unique aspects, each of which works to overcome some pertinent challenges associated with the recovery of defaced serial numbers. Infrared thermal imaging of metal surfaces provides thermal images sensitive to local differences in thermal conductivity of regions of plastic strain existing below a stamped number. These strains are created from stamping pressures distorting the atomic crystalline structure of the metal and extend to depths beneath the stamped number. These thermal differences are quite small and thus not readily visible from the raw thermal images of an irregular surface created by removing the stamped numbers. As such, further enhancement is usually needed to identify the subtle variations. The multivariate data analysis method, principal component analysis, is used to enhance these subtle variations and aid the recovery of the serial numbers. Multiple similarity measures are utilised to match recovered numbers to several numerical libraries, followed by application of various fusion rules to achieve consensus identification.

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Section: Introductionmentioning

confidence: 99%

“…Approaches used for the recovery of obliterated serial numbers leverage such differences to recover the numbers. [1][2][3][4][5][6] A widely used approach is chemical etching. This process utilises the change in chemical potential that makes the defaced area more reactive to acids, allowing recovery of serial numbers.…”

Section: Introductionmentioning

confidence: 99%

Restoration of defaced serial numbers using lock-in infrared thermography (Part I)

Unobe

Lau

Kalivas

et al. 2019

J. Spectral Imaging

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“…Com base nesse cenário, a recuperação de marcações originais é de comum ocorrência na investigação realizada pelos peritos criminais brasileiros, pois ela fornecerá fortes evidências que auxiliarão na recuperação do veículo e na busca pelos infratores. (1,2) A pesquisa em torno da caracterização de códigos adulterados é focada na detecção da zona de deformação plástica ou zona de tensões residuais, a qual está situada na região imediatamente abaixo da cavidade, criada pela impressão, e sua extensão é fortemente dependente das propriedades do material. Em adição, no momento da adulteração, as marcações originais são removidas ou recobertas sendo comum a remanescência de parte da zona de deformação plástica, mesmo após a remoção da cavidade.…”

Section: Introductionunclassified

Estudo De Técnicas Não Destrutivas Na Recuperação De Marcações Adulteradas Em Chapas De Baixo Carbono E Ultrabaixo Carbono

Lima¹,

Pacheco²,

Nóbrega³

et al. 2019

ABM Proceedings

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Resumo O presente trabalho teve o objetivo de avaliar a aplicabilidade das técnicas não destrutivas de partículas magnéticas e visualização magneto-óptica na prática de investigação veicular, especificamente na área de recuperação de marcações adulteradas. As amostras utilizadas nesse estudo foram extraídas de partes do chassi de dois veículos. Com a finalidade de determinar os materiais, dos quais foram fabricados os chassis estudados, foi necessária a caraterização prévia dos mesmos através de análise química, magnética, mecânica e microestrutural. Em seguida, as amostras foram identificadas por estampagem e adulteradas por remoção e remarcação. As técnicas não destrutivas foram avaliadas de acordo com a definição dos códigos revelados e o tempo de análise. Com base nos resultados obtidos, as técnicas magnéticas não destrutivas apresentaram desempenho satisfatório na recuperação das marcações originais das amostras adulteradas.

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“…It has wide range of application in forensic science. It has been used successfully in examination of footwear impression (Morgan et al, 2009), facial reconstruction (Stephan & Henneberg, 2001;Benazzi et al, 2009;Claes et al, 2006;Cesarani et al, 2004;George, 1987), forensic ballistics (Jain et al, 2004;Hejna & Safr, 2009), restoration of obliterated marks (Kuppuswamy, 2011), tool mark impression (Rees, 1969) and Odontology (Gorea et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Development of firing pin and breech face impression on lead and plasticine surfaces- a case report

Sehgal

Sahota

Kaur

et al. 2017

Egypt J Forensic Sci

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Background: The microscopic examination of fired cartridge cases and fired bullets helps the expert to determine if a suspect firearm/firearms were, or were not, discharged in a shooting incident. This is achieved by using a combination of class and individual characteristics. But in case of malfunctioning of firearm, experts have to adopt different methods to link fired cartridge cases and fired bullets with the suspected firearm. Case presentation: In this paper, a new method for the reproduction of the firing pin and breech face impression on two different surfaces are reported. Two chosen surfaces are plasticine and lead metal. Conclusions: The surface of the lead being soft and brittle reproduced the impression with maximum detail. Five match points were seen on the lead surface with clear demarcation whereas only three points of individual characteristics marks were observed on plasticine surface.

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Metallographic Etching of Aluminium and Its Alloys for Restoration of Obliterated Marks in Forensic Science Practice and Investigations

Cited by 12 publications

References 28 publications

Restoration of defaced serial numbers using lock-in infrared thermography (Part I)

Restoration of defaced serial numbers using lock-in infrared thermography (Part I)

Estudo De Técnicas Não Destrutivas Na Recuperação De Marcações Adulteradas Em Chapas De Baixo Carbono E Ultrabaixo Carbono

Development of firing pin and breech face impression on lead and plasticine surfaces- a case report

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