Restoration of obliterated numbers on 40NiCrMo4 steel by etching method [Recurso eletrónico] : metallurgical and statistical approaches / Annalisa Fortini... [et al.]
Autor institucional: RESTORATION OF OBLITERATED NUMBERS ON 40NICRMO4 STEEL BY ETCHING METHODIn: Journal of Forensic Sciences.ISSN 1556-4029. Hoboken. Vol. 61, n. 1 (January 2016) , p. 160-169Idioma: Inglês.Assunto: VEÍCULO AUTOMÓVEL | MARCAÇÃO DE OBJECTOS | CIÊNCIA FORENSE | QUÍMICA FORENSE | ESTATÍSTICA Resumo: The restoration of obliterated serial numbers is a problem of common occurrence in the forensic field. Among several restoration techniques, chemical etching is the most frequently used. The present research is aimed at studying the restoration of serial numbers, stamped on 40NiCrMo4 steel plates, by means of chemical etching. Microstructural characterization was firstly carried out to study the plastically deformed regions surrounding the marks. The obliteration was performed by controlled removals of material at increasing depths of erasure, and five etching reagents were considered to analyze their sensitivity and effectiveness. Experimental results revealed that Fry’s reagent was the most sensitive, able to restore erased marks up to 60 lm under the depth of the imprint. The reagent comprising 25 mL HNO3 and 75 mL H2O provided good results, recovering the major numbers of characters. A descriptive statistical analysis was conducted to study the operator’s influence on the recovered marks’ identification.| Item type | Current location | Call number | Status | Date due | Barcode |
|---|---|---|---|---|---|
| Analíticos de Periódicos | Biblioteca da Polícia Judiciária | Available |
(*) CD 294. Resumo inserto na publicação. Ficheiro de 1,79 MB em formato PDF (10 p.).
The restoration of obliterated serial numbers is a problem of common occurrence in the forensic field. Among several restoration techniques, chemical etching is the most frequently used. The present research is aimed at studying the restoration of serial numbers, stamped on 40NiCrMo4 steel plates, by means of chemical etching. Microstructural characterization was firstly carried out to study the plastically deformed regions surrounding the marks. The obliteration was performed by controlled removals of material at increasing depths of erasure, and five etching reagents were considered to analyze their sensitivity and effectiveness. Experimental results revealed that Fry’s reagent was the most sensitive, able to restore erased marks up to 60 lm under the depth of the imprint. The reagent comprising 25 mL HNO3 and 75 mL H2O provided good results, recovering the major numbers of characters. A descriptive statistical analysis was conducted to study the operator’s influence on the recovered marks’ identification.
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