Study of the Chemical Composition of a Steel Wire Brass Coating for Steel Cord Production

The purpose of the study is to identify transitional diffusion layers in the steel wire-brass coating system. Brass-plated wire is used in the production of steel cord. The authors use brass-plated wire made of steel 80 by dry drawing, two-stage deposition of a brass coating (copper + zinc), and subsequent diffusion annealing. The chemical composition is determined with a scanning electron microscope TESCAN Vega3 SBH equipped with a device for X-ray microanalysis (MRSA) by Oxford Instruments using framing to obtain elements distribution maps. In the study of the chemical composition of the steel wire brass coating under the metal cord, the copper concentration gradient is determined from the spectra, the iron content in the coating and the copper content in the steel core are established. The authors determine the presence of a transitional diffusion layer from a brass coating to a steel core of a wet-drawn wire with a diameter of 1.67 and 1.85 mm in two sections with different thicknesses of a brass coating in opposite sections (maximum and minimum). The article contains an elemental distribution map of Fe, Cu and Zn, as well as a general superposition map of Fe, Cu and Zn. Graphs of the content for two studied cross sections are presented. The transition diffusion layer has a gradient transition in the concentrations of Fe, Cu and Zn, which characterizes a good connection of the brass coating with steel. The diffusion layer of the brass coating of a steel wire with a diameter of 0.30 mm, produced by wet drawing of a steel wire with a diameter of 1.67 mm, is studied. A coating image is obtained by framing. The coating thickness along with the diffusion layer has an average value of 1.4 μm with an apparent coating thickness of 0.5 μm.