High Temperature Oxidation of Indefinite Chill Roll Material Under Dry and Humid Atmospheres

Abstract

In this paper, the isothermal oxidation of the indefinite chill (IC) roll is investigated by using a thermogravimetric analyzer (TGA) from 550 to 700 °C under dry and humid atmospheres. It is found that the oxidation kinetics follow a linear trend and the oxide scale consists of two layers after the oxidation in dry air but three layers in humid air above 600 °C. In dry air, the graphite is covered by the oxide scale above 650 °C. The water vapor accelerates the oxidation of the matrix and the graphite. The graphite is covered by the extension of the oxide scale above 600 °C in humid air. The as‐treated samples are examined with SEM and XRD, while the kinetics is based on TGA results.

Wear and friction behaviour of high-speed steel and indefinite chill material for rolling ferritic stainless steels

“…Because the numbers of cobbles, double folded strip and tail end pinches increase in the later stands of a hot strip mill, mechanical cracks seem to grow deeper in HSS than that in IC rolls [6]. Moreover, during the hot rolling of stainless steels, it is also reported that the sticking defects are obviously improved with the application of IC rolls, since the graphite in the IC materials can retard crack propagation and reduce friction [7][8][9].…”

“…Image analysis of its BSE image reveals that the total area fraction of these carbides is 12.5%, including 8.5% MC and 4.0% M 7 C 3 and M 6 C. In addition, there are three different phases(Fig. 2b), graphite, cementite (Fe 3 C) and tempered martensite in the IC[7], comprising 4.3% graphite and 20.8% cementite. The HSS has a high hardness of 760 HV whereas the IC has a lower hardness of 633 HV.…”

The Oxidation Behaviors of Indefinite Chill Roll and High Speed Steel Materials

“…The mass variations were recorded in this process. The air containing 20% water vapor was obtained by setting the temperature of the water tank at 60 • C [31].…”

“…Figure 7 shows SEM images of the IC cross section of the matrix regions and the graphite areas oxidized at 700 • C in both dry and humid air. As the IC rolls oxidized in the dry air (Figure 7a,b), two relatively thin oxide scales can be observed, namely a thin Cr-rich (FeCr) 3 O 4 layer next to the substrate, and an outer layer of hematite (Fe 2 O 3 ) [31]. The oxidation of graphite is known as decarburization and left an amount of cavities, which were filled by the extension of the oxide scales.…”

Effect of Chromium and Water Vapor of Low Carbon Steel on Oxidation Behavior at 1050 °C

“…Wei et al investigated the effect of water vapor content on high‐temperature oxidation behavior of stainless steels by using the water vapor content from 2.8 to 19.5 vol%. Literatures also reported the influence of water vapor on oxidation process of different steels and illustrated that water vapor as corrosive gas in high‐temperature oxidation process changes the oxidation behavior of metals compared to dry air. Therefore, it is essential to understand the effect of water vapor on the high‐temperature oxidation behavior of Cr‐containing steels because water vapor can play the key role in changing the oxidation behavior.…”