Application of a new reagent for analysis of oxygen presence in a low-carbon steel wire rod

A microstructural analysis was performed to determine the presence of oxygen in a wire rod section of AISI 1008 steel with a surface mechanical failure produced during wire drawing. The failure zone was analyzed by comparison using three different attack reagents: alkaline sodium chromate (ASC), ASC with hydrogen peroxide and amyl alcohol, and a solution of nitric acid in ethyl alcohol. The reagents were applied in samples in the failure zone, showing different types of zones in regions with internal and superficial defects such as carbides, pores, cracks, deformation, and detachment zones, indicating the possible presence of oxygen. The areas identified were observed by means of an optical microscope and were correlated with the content of elements that were present in the region using a scanning electron microscope and a scattered X-ray energy spectrometer, which determined that the areas identified by chromate sodium correspond to regions with a high concentration of oxygen and slag-forming elements such as silicon, aluminum, and iron; this is associated with the presence of oxygen in the oxide form. It was also observed that the ASC and the modified ASC solution with hydrogen peroxide and amyl alcohol could identify areas with a high presence of oxides, while the nitric acid solution only identified the steel microstructure. The modified ASC solution is an alternative to identify the presence of chemical variants of oxygen because the conventional formulation is unstable and has a too short shelf life, and therefore, its application must be carried out at the time of preparation.