Investigation of Structure, Chemical and Phase Composition of Silicon Spring Steel Scale
Abstract
The article presents the results of investigation of structure, chemical and phase composition of scale formed on siliceous spring steels during high-temperature heating prior to rolling. It is established that in 40S2 steel, the hematite layer bordering furnace atmosphere has a minimum thickness of about 40–60 μm, the magnetite layer has thickness of 250 ± 280 μm, the largest thickness of 800 ± 900 μm has wustite layer with secondary ferriferous oxide released during cooling, bordering the steel surface. The scale layer adjacent to the steel surface is characterized by a much greater macrostructural, chemical, and phase inhomogeneity. In addition to
wustite–ferriferous oxide mixture, iron silicates with an increased silicon content are present. Approaching the steel surface, the number of zones enriched with silicon increases. When 60S2ChA steel is heated to 1180–1200∘С, zones enriched with silicon are observed in the scale at a distance of 200 ± 250 μm from the metal surface, and when heated to temperatures of 1310 ± 1315∘C at a much larger distance, reaching
700–800 μm.
Keywords: scale, steel heating, siliceous springs steel, scale microstructure
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