Effect of Chromium Content on the Oxidation Behaviour of High-Speed Steels under Dry and Moist Air Environments

Abstract

Development and use of high-speed steels for manufacturing the roll outer shell of hot strip mills represented a major recent technological advancement in the hot rolling field. However, it was observed that the oxidation behavior of these steels was different from that of conventional rolls. The high-speed steel oxidation rate is about four times higher than the alloys previously used. Furthermore, the rolling conditions are quite aggressive. Contact of the roll with the hot strip, air and water of the cooling system is expected to increase the oxidation of the roll surface in this wet atmosphere. Therefore, it is necessary to study their oxidation behavior in order to achieve the full potential of high-speed steel rolls for hot strip mills. In the present work, the oxidation behavior of three high-speed steels with differences in chromium content was studied. Corrosion tests were carried out in a thermobalance under dry and moist (12.5 % H2O) atmospheres at 765oC for 240 minutes. The corroded samples were examined by X-ray diffraction, scanning electron microscopy and energy dispersive micro-analysis. It was found that the variation of chromium content of the high-speed steels studied was sufficient to influence the oxidation behaviour. Samples with high chromium contents presented smallest final mass gain. The presence of humidity had a significant effect on the oxidation behavior.

Fluctuations in Chemical Composition of M7C3 Carbides in the Soft Annealed Nc11lv/D2 Steel

“…Of particular note are the conditions for the micro beam analysis of the carbide composition. Our findings, indicating that chromium is uniformly distributed whereas molybdenum showed worst uniformity, have been confirmed also concerning the results obtained for other steel alloys, with the supporting data given in [13,[17][18][19][20][21].…”

“…Prolonged low-temperature gas-phase carburization of AISI 316L-type austenitic stainless steel can cause intragranular precipitation of the carbide M 7 C 3 (M: randomly dispersed Fe, Cr, Ni); the effect was observed by Ernst et al [16] . Effect of chromium content on the oxidation behaviour of high-speed steels under dry and moist air environments was studied by Monteiro and Rizzo [17]. Compositional changes in carbide M 7 C 3 upon annealing and the effect of Cr content on microstructure and properties of medium-alloy high carbon tool and die steel were studied by Palcut et al [18], and Zhang et al [19], respectively.…”

Theoretical and experimental investigation of thermal and oxidation behaviours of a high speed steel work roll during hot rolling

“…Zhou et al [43,44] have compared the oxidation rate of a HSS material at different temperatures and they have concluded that the matrix was easier than the carbides to be oxidized at low temperatures. However, their conclusions obviously contradict with the results shown in [37][38][39][40]45]. In addition, Yin et al [46] have recently reported that the HSS oxide scale thickness was as large as 5 μm after 2 hours oxidations below 600 °C.…”

“…For example, Kim et al [37] have reported a significant influence of alloy elements vanadium (V) and chromium (Cr) by oxidizing three different HSS materials at 600°C. More details can be found in [38][39][40], where Cr-rich M 7 C 3 carbide had the best oxidation resistance than carbides MC and M 2 C because it dissolved high amount of chromium. Those observations were confirmed by the recent studies [41,42] by analyzing the morphology and microstructure evolutions of oxidized HSS samples.…”

Effect of High-Temperature Heating on Chemical Changes in M₇C₃ Carbides of AISI D2 Tool Steel

“…Many investigators were dealing with the study of structure and chemical composition of chromium-iron carbides [36][37][38][39][40][41][42][43][44][45][46][47][48][49]. The main aim of this work, with the results presented herewith, was to establish the behavior of chromium, molybdenum and vanadium in M 7 C 3 carbides occurring in NC11LV (160H12MF) steel austenitized at 1150 ºC.…”