High-temperature Oxidation Of Steel Research Articles

Influence of silicon and tramp elements on the high-temperature oxidation of steel in direct casting and rolling processes

Influence of silicon and tramp elements on the high-temperature oxidation of steel in direct casting and rolling processes

High-Temperature Oxidation of Steel under Linear Flow Rates of Air and Water Vapor—An Experimental Determined Set of Data

High-temperature oxidation phenomena play a crucial role in steel production and processing. The development of new alloying concepts, the modification of production routes due to the decarbonization of steelmaking, and increasing quality demands will additionally stimulate research activities on high-temperature oxidation. Within the scope of this publication, the oxidation behavior of an unalloyed steel was investigated by means of thermogravimetric (TG) and metallographic analysis. The TG measurements were performed with a simultaneous thermal analyzer in combination with a water vapor generator and a mass spectrometer for quality control. Experiments were conducted in a temperature range from 900 to 1200 °C under various oxidation atmospheres, containing synthetic air and water vapor, with different linear flow rates of the oxidizing medium. According to the thermogravimetric data, an evaluation method is introduced to obtain direct kinetic data for linear and parabolic scale growth. The influence of the experimental parameters on high-temperature oxidation is discussed in detail.

Initial High-Temperature Oxidation Behavior of Fe–Mn Binaries in Air: The Kinetics and Mechanism of Oxidation

High-temperature oxidation of steels can be relatively fast when exposed to air. Consequently, elucidating the effect of different parameters on the oxidation mechanism and kinetics is challenging. In this study, short-time oxidation was investigated to determine the oxidation mechanism, the affecting parameters, and the linear-to-parabolic growth transition of different Fe–Mn alloys in various oxygen partial pressures (10–30 kPa) and gas flow rates (26.6 and 53.3 sccm) in a temperature range of 950–1150 °C. Oxidation kinetics was investigated using a thermogravimetric analyzer (TGA) under controlled atmosphere. Linear oxide growth was observed within the first 20 minutes of oxidation. The linear rate constant was significantly increased by increasing the oxygen partial pressure or the flow rate of the oxidizing gas. The morphology of the oxide layer was determined by scanning electron microscopy (SEM). The crystal structure of the oxides formed was followed by in-situ X-ray diffraction (XRD), confirming that the growing layer consists of wustite mainly, which upon slow cooling to room temperature, transformed into magnetite. Energy-dispersive X-ray spectroscopy (EDS) showed that the atomic ratio of Fe+Mn to O was ~ 1.03:1 in the oxide scale, corresponding to Fe(Mn)O formation. Based on the characterization and a model for linear growth kinetics, it is concluded that the oxidation rate is controlled by the diffusion of oxidizing molecules through the gas layer to the sample’s surface. The findings led to a better understanding of initial oxidation behavior and provided a pathway for improved insight into the high-temperature oxidation behavior for more complex alloys.

High-Temperature Oxidation of Steels in Direct-Fired CO2 Power Cycle Environments

Future direct-fired supercritical CO2 power cycles require steels resistant to oxidation/corrosion in high-temperature CO2 environments containing various impurities. Herein we studied the oxidation behavior of 14 candidate steels in a simulated direct-fired CO2 power cycle environment consisting of 95% CO2, 4% H2O, 1% O2 with/without 0.1% SO2 at 1 atm and 550 °C, 600 °C, 650 °C for up to 2500 h. Steels with ≥ 11.5 wt% Cr exhibited at least partial coverage by Cr-rich oxide scales leading to a significant decrease in the oxidation rates in both gases. While SO2 had little effect on low-Cr steels that formed Fe-rich oxides, it generally worsened performance of high-Cr (> 11.5 wt%) steels by hindering the establishment of a protective Cr-rich oxide. This effect was most pronounced at the lowest temperature of 550 °C, which was attributed to strong preferential adsorption of sulfur-containing species within the oxide at relatively low temperatures.

Oxidation Induced Stresses in High-Temperature Oxidation of Steel: A Multiphase Field Study

Oxide growth and the induced stresses in the high-temperature oxidation of steel were studied by a multiphase field model. The model incorporates both chemical and elastic energy to capture the coupled oxide kinetics and generated stresses. Oxidation of a flat surface and a sharp corner are considered at two high temperatures of 850 °C and 1180 °C to investigate the effects of geometry and temperature elevation on the shape evolution of oxides and the induced stresses. Results show that the model is capable of capturing the oxide thickness and its outward growth, comparable to the experiments. In addition, it was shown that there is an interaction between the evolution of oxide and the generated stresses, and the oxide layer evolves to reduce stress concentrations by rounding the sharp corners in the geometry. Increasing the temperature may increase or decrease the stress levels depending on the contribution of eigen strain in the generated elastic strain energy during oxidation.

High temperature oxidation of steels in CO2 containing impurities

Future power systems require steels that resist corrosion in high temperature CO2 containing combustion products/impurities. Here we evaluate the corrosion behavior of several commercial steels exposed to 95% CO2-4 % H2O-1 % O2, with/without 0.1 % SO2, at 550 °C and 1 atm. High-Cr steels formed thin Cr-rich oxides and low-Cr steels thick Fe-rich oxides during SO2-free exposures. Additions of SO2 had little effect on low-Cr steels but enhanced corrosion of high-Cr steels, where S within the chromia scale led to its failure and subsequent Fe-rich oxide nodule growth. The results are rationalized by considering the thermodynamic and kinetic factors controlling the reaction.

Effect of Surface Finish on High-Temperature Oxidation of Steels in CO2, Supercritical CO2, and Air

Current and future power systems require steels resistant to high-temperature oxidation in CO2-rich environments. The introduction of structural defects by various surface treatments can profoundly affect the oxidation/corrosion behavior of steels in many environments. This effect is largely unexplored for steels exposed to high-temperature CO2, which is the focus of this work. We prepared Grade 22, Grade 91, 347H, and 310S steels with three different surface finishes, ranging from little to substantial surface damage, and exposed the steels to 1 bar CO2, 200 bar supercritical CO2, and laboratory air at 550 °C for up to 1500 h. Surface finish had little impact on the oxidation behavior of low-Cr (2 wt%) Grade 22 and high-Cr (25 wt%) 310S steels. In contrast, intermediate-Cr steels Grade 91 (8 wt%) and 347H (17 wt%) generally showed improved oxidation and carburization resistance with increasing extent of surface damage, which was attributed to the delay or prevention of the onset of Fe-rich oxide nodule growth. Comparison between exposure environments suggests that this effect is more complex for CO2 compared to air and that it is additionally affected by CO2 pressure. The results suggest that surface treatments should be considered as one approach to achieve improved corrosion resistance in high-temperature CO2, particularly for steels containing Cr levels near the transition that is required to form and maintain a protective Cr-rich oxide scale.

FRONT MATTER

<p><strong>PREFACE</strong></p><p>Indonesian Journal of Science and Technology (IJoST) is a peer-reviewed journal that aims to publish and disseminate innovative research articles on the latest developments in all fields of science and technology. The journal publishes original papers in English, which contribute to the understanding of science and improvement of the science and technology. Papers may be theoretical explanation (including computational), experimental observation and analysis, or combination from both theoretical and experimental analysis. The contribution should be unpublished before and not under consideration for publication in elsewhere. IJoST maintains a standard double-blind peer review process. The review process means that the identity with the author, and the reviewer are not known to each other. IJoST is an open-access journal, and in this issue IJoST does not charge for readers, authors, or their institutions for access to the journal articles. This journal was firstly be published on April 30, 2016, and issued every April and October in each year, published by Tim Pengembang Jurnal at Universitas Pendidikan Indonesia.</p><p>In this issue, we published eight papers, including six original research articles and two review papers. In this issue, we received papers from remarkable researchers in several countries in the world, including Belgium, Japan, Singapore, Malaysia, The Netherlands, and Indonesia. The first paper discussed enzymatic cleaning method for reducing membrane fouling in membrane bioreactor. The next paper presented about application of artificial neural network for predicting biodiesel production. In the third paper, authors discussed about comparison of air temperature under global climate change in Japan. In the fourth paper, authors discussed about kinetics and thermodynamic studies the adsorption of phenol on activated carbon. The fifth article presented sludge dewatering process control using principal component analysis and partial least square. The next paper discussed the use of process simulation for plant debottlenecking. The sixth paper is a review article regarding the use of agricultural waste for silica source material. The final paper is a review of high-temperature oxidation of steel in steam condition. We believe that this issue will give benefits for the improvement and the development of science and technology.</p><p> </p><p align="right">Bandung, April 2006</p><p align="right"> </p><p align="right">Editor</p><p align="right"> </p><p> </p>

Effect of Si on High-temperature Oxidation of Steels during Reheating and Hot Rolling

Effect of Si on High-temperature Oxidation of Steels during Reheating and Hot Rolling

高温酸化スケールのブリスタリングの成長過程に及ぼす窒素の影響

高温酸化スケールのブリスタリングの成長過程に及ぼす窒素の影響

Effect of Nitrogen on Blister Growth Process during High Temperature Oxidation of Steel

Effect of Nitrogen on Blister Growth Process during High Temperature Oxidation of Steel

Role of Hematite Formation on Blister Generation during High Temperature Oxidation of Steel

Blistering is a phenomenon in which oxide scale swells during oxidation at high temperatures. Blistered scale causes surface defects in steel products during hot-rolling processes. The present study investigated the effect of oxygen and the scale layer structure on blister initiation when steel is oxidized at high temperatures, and the mechanism of blister formation is discussed. The following conclusions are drawn. Blisters are not formed when the scale is a wustite mono-layer, but start to nucleate when the scale layer structure changes from the wustite mono-layer to a three-layered scale comprised of hematite (Fe2O3), magnetite (Fe3O4), and wustite (FeO). The compressive stress in the oxide scale that is applied due to the oxide scale growth is largely released when scale layer structure changes from the wustite mono-layer to the three-layered scale. This result suggests that the compressive stress is not the main factor for blister initiation. It is deduced that the pressure of the CO, CO2, and N2 gases generated at the scale/steel interface is the main factor for blister formation. The hematite layer on the top surface of scale presumably acts as a barrier of gas permeability.

Sol–gel coating to reduce 1.25Cr–0.5Mo steel oxidation at 700 °C: Catalyst type effect

With the use of sol–gel it is possible to apply zirconia coatings to reduce high temperature oxidation of steel. Some limitations of this technique are high hydrolysis rates and the formation of cracks during the drying stage. In this work, the mole ratio of zirconium butoxide to ethylacetate, and the nature of the catalyst were varied. SEM-EDX was used to evaluate the continuity of the zirconia coatings, and thermo-gravimetric analysis for the oxidation rate of coated samples. Thin and continuous coatings were obtained. With a basic catalyst, the coatings were crack-free and presented lower oxidation rate than acid-catalyzed coatings.

Influence of water vapour on high temperature oxidation of steels used in petroleum refinery heaters

The oxidation behaviours of three different steels used in the construction of petroleum refinery heaters were investigated by thermogravimetric analysis (TGA) technique. C-5, P-11 and P-22 steel samples were tested in two different environments: air and CO2 + 2H2O + 7.52N2, a gas composition which simulates the combustion products of natural gas, at 450 and 500 °C. P-22 steel had the best oxidation resistance at both temperatures in air. In CO2 + 2H2O + 7.52N2 environment, the oxidations of all the steels were accelerated and C-5 exhibited better oxidation resistance than P-22 and P-11. Analyses of oxidation products by optical microscopy, SEM-EDX and XRD were carried out to correlate TGA results to oxide composition and morphology. The lower oxidation rate of P-22 in air was explained with reference to the formation of a protective Cr-containing oxide layer between the steel and the iron oxide scale. The higher oxidation rates of chromium containing steels in CO2 + 2H2O + 7.52N2 environment were attributed to the depletion of protective Cr-containing oxide scale, which was deduced from the lower Cr content of this layer than that formed in air oxidation, as a result of probably faster oxidation of Cr even inside the steel. Therefore, the oxidation mechanisms of FeCr alloys with intermediate Cr contents at higher temperatures could also be valid for steels with low chromium contents such as P-22 (2.25%) even at 450 and 500 °C.

Effect of Si on High-Temperature Oxidation of Steel during Hot Rolling

An oxide scale layer always forms at the strip surface during the hot rolling process. As a consequence, de-scaling and pickling operations must be performed prior or after hot rolling. Many surface defects caused by hot rolling are related to oxidation in the reheating furnace. One of these is the melting of eutectic FeO/Fe2SiO4 during reheating over 1170°C giving as a result red scale defects in Si-added steel. On the other hand, steel strip surface oxidation during hot rolling causes an industrial and environmental problem: secondary oxide is removed after roughing, but tertiary oxide scales already start to form before entering the finishing stands. Their properties affect the final steel surface quality and its response to further processing. Furthermore, the addition of alloying elements has an important impact on scale properties. In particular the alloying of silicon effects the region between scale and substrate. It causes peculiar surface properties inherited from its specific oxidation characteristics. Conventional oxidation experiments in air of silicon steels are a valuable tool to study the influence of Si on steel oxidation. After oxidation in air in the temperature range of 900-1250°C it has been observed that Si enhance markedly scale adhesion, especially above 1177°C (the eutectic temperature of FeO-Fe2SiO4 ) and also at lower temperatures. Special attention has been paid on the investigation of the effects of alloying Si on the high-temperature oxidation of steel, for a better understanding of the behaviour of modern steels during hot rolling.

High Temperature Oxidation of Steel; New Description of Structure and Properties of Oxide

The quality of steel sheets is strongly affected by the surface defects that can be generated during hot rolling and are often related to scales removal operation. These defects are related to rather complex high temperature oxidation processes. In order to reduce an occurrence of the defects, it is necessary to understand better the formation of iron oxides during high temperature oxidation, the structure of the interfaces with the substrate and between different oxide phases. However, due to the lack of good experimental research tools details of iron oxide microstructures were not investigated. Conventional methods, such as backscattered electron images or fractography can only provide general characteristics of microstructures like grain morphology and grain size. In this paper the microstructure, phase distribution and texture in oxide formed during high temperature oxidation of iron and low carbon steels are investigated. The oxide microstructures are characterized by orientation imaging microscopy (OIM) on the cross-sectional area of the oxide layers. It is demonstrated that OIM using electron backscattered diffraction (EBSD) techniques, can be used to distinguish grains having different phase composition and orientation and can become invaluable tool for visualizing the oxide microstructure, texture and also can be used to study oxide defects. The three different iron oxides phases can be distinguished and the characteristics of oxides with different oxidation histories compared The characteristics of high temperature oxidation microstructure of iron are presented with description of iron oxide defects and cracking as well as the illustration of the interfacial microstructure between the layered iron oxides.

High Temperature Oxidation of Steels in Air and CO2–O2 Atmosphere

Three kinds of hot rolled steel slabs, viz. high strength steel, bake hardened steel and low carbon steel, were oxidized isothermally between 1100 and 1250 °C for up to 2 hr in 1 atm of air and an 85%N2–10%CO2–5%O2 gas mixture. The steels were oxidized in a similar fashion in both the atmospheres. The oxidation process followed an initial linear rate law, which then gradually transformed to a nearly parabolic rate law. Thick, porous and nonadherent scales formed rapidly, due to the high oxidation temperature. The scales formed consisted of Fe2O3,(Fe2O3+Fe3O4), (Fe3O4+Fe2O3 +FeO) and (FeO+Fe3O4) from the outer surface. The presence of supersaturated oxygen beneath the scale resulted in grain boundary oxidation and the formation of internal oxide precipitates.

Microstructural and microtextural characterization of oxide scale on steel using electron backscatter diffraction.

High-temperature oxidation of steel has been extensively studied. The microstructure of iron oxides is, however, not well understood because of the difficulty in imaging it using conventional methods, such as optical or electron microscopy. A knowledge of the oxide microstructure and texture is critical in understanding how the oxide film behaves during high-temperature deformation of steels and more importantly how it can be removed following processing. Recently, electron back-scatter diffraction (EBSD) has proved to be a powerful technique for distinguishing the different phases in scales. This technique gives valuable information both on the microstructure and on the orientation relationships between the steel and the scale layers. In the current study EBSD has been used to investigate the microstructure and microtexture of iron oxide layers grown on interstitial free steel at different times and temperatures. Heat treatments have been carried out under normal oxidation conditions in order to relate the results to real steel manufacturing in industry. The composition, morphologies, microstructure and microtexture of selected conditions have been studied using EBSD.

Behaviour of Copper during High Temperature Oxidation of Steel Containing CopperYasumitsu KONDO

It is well known that copper causes the hot shortness problem in steels and is a difficulty when using steel scrap in the steelmaking process. This is due to the property of copper enriching at the scale/metal interface and precipitating there as liquid during the high temperature oxidation of steels containing copper. In this paper, the behaviour of copper during oxidation is investigated. A steel containing copper is oxidized and the distribution of copper in the scale is examined. It is found that copper is not only enriched at the scale/metal interface, but also exists in the upper magnetite (Fe 3 O 4 ) layer as a state of solid solution and along the grain boundaries of the wustite layer as a metal. From these results an assumption has been proposed that the liquid copper migrates from the scale/metal interface to Fe 3 O 4 layer along the grain boundaries. Quantitative analysis revealed that the copper amount in the scale is greater than that at the scale/metal interface. Further analysis discovered that the amount of copper eliminated from the steel by oxidation is greater than the total amount of copper detected in the sample i.e. at the scale/metal interface, in the Fe 3 O 4 layer, and along the grain boundaries in the scale.

Behaviour of copper during the high temperature oxidation of steels produced by the electric furnace route

The surface quality of hot rolled low-carbon steels may be affected by their copper content when it exceeds 0.3% by weight. At high temperature (more than 1200 °C), a large part of the non oxidized copper is occluded into the primary scale and hot shortness phenomenon is prevented. At lower temperature (around 1000 °C), surface cracking may occur because Cu enrichment at the scale/steel interface cannot be avoided. Then the running risk depends on time and respective contents in Cu, Ni and Sn.