01825nam a2200181   4500001000700000100004100007101000800048200017200056311009400228330103400322461009401356606002601450606002901476606002201505606002201527606001801549710007601567376010  a20151020u           y0pory50      ba  aeng  aRestoration of obliterated numbers on 40NiCrMo4 steel by etching methodbRecurso eletrónicoemetallurgical and statistical approachesfAnnalisa Fortini... [et al.]    a(*) CD 294. Resumo inserto na publicação. Ficheiro de 1,79 MB em formato PDF (10 p.).  aThe 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.  cHobokendJanuary 2016vVol. 61, n. 1tJournal of Forensic Sciencesx1556-4029pp. 160-169  aVEÍCULO AUTOMÓVEL  aMARCAÇÃO DE OBJECTOS  aCIÊNCIA FORENSE  aQUÍMICA FORENSE  aESTATÍSTICA  aRESTORATION OF OBLITERATED NUMBERS ON 40NICRMO4 STEEL BY ETCHING METHOD