The Effect of the Si Content on the Morphology and Amount of Fe2SiO4 in Low Carbon Steels

Abstract

In order to study the effect of the Si content on the morphology, amount, and distribution of fayalite (Fe 2 SiO 4 ), three low-carbon steels with different Si contents were selected, and reheating tests were conducted in an industrial furnace in a hot strip plant. The results show that Si distributes in two forms-first, Fe 2 SiO 4 , in the innermost layer of the oxide scale, and, second, granular SiO 2 , dispersively distributed in the matrix near the scale. In addition, Fe 2 SiO 4 appears in a net-like form in the innermost layer of the oxide scale close to the iron matrix when the Si content is 1.21 wt. %. However, no obvious net-like Fe 2 SiO 4 is observed when the Si content is less than 0.25 wt. %. Moreover, the inhibition effect of the solid Fe 2 SiO 4 on the oxidation reaction plays a more important role than the promotion effect of the liquid Fe 2 SiO 4 during the entire oxidation reaction. Therefore, the total thickness of the scale decreases with the increase in Si content.

The Effect of P on the Microstructure and Melting Temperature of Fe2SiO4 in Silicon-Containing Steels Investigated by In Situ Observation

“…Initially, the total area of Fe2SiO4 in the inner layers is isolated and measured by the auto-discernment function of color aberration in the software. Subsequently, to obtain the areas of Fe2SiO4 in unit widths, the total areas are divided by the width of the measured images [11]. The red area represents the distributions of solid Fe2SiO4 and the measured area can represent the amount of Fe2SiO4.…”

“…Mouayd et al [10] reported that the penetrative depth of the eutectic FeO/Fe 2 SiO 4 in the scale increases with the silicon content. In the present authors' previous study [11] on the relationship between silicon content and morphology of Fe 2 SiO 4 , it was shown that Fe 2 SiO 4 appears in a net-like form in the innermost layer of oxide scale close to the iron matrix when the silicon content is 1.21 wt %. However, no obvious net-like Fe 2 SiO 4 is observed when the silicon content is less than 0.25 wt %.…”

The Morphologies of Different Types of Fe2SiO4–FeO in Si-Containing Steel

“…Previous studies have confirmed that the iron scale in this steel contains Fe 2 O 3 , Fe 3 O 4 , FeO, and Fe 2 SiO 4 [11,14,15]. The intimal scale consists of Fe 2 SiO 4 and FeO.…”

“…Yuan et al [11] reported that the net-like morphology of Fe 2 SiO 4 -FeO is not obvious when the Si content is low. Mouayd et al [12] and Suarez et al [13] found that the amount and penetrative depth of Fe 2 SiO 4 -FeO increases with the Si content.…”

“…Due to the close relationship between red scale and Fe 2 SiO 4 -FeO, some studies on Fe 2 SiO 4 -FeO in Si-containing steels have been carried out [11][12][13][14]. Yuan et al [11] reported that the net-like morphology of Fe 2 SiO 4 -FeO is not obvious when the Si content is low.…”