Oxidation Of Low-carbon Steel Research Articles

High temperature oxidation behaviors of steels at initial stages in air

The initial stage oxidation behaviors of commercial low carbon steel (LCS) and advanced high strength steel (AHSS) were comparatively studied at 1150 °C in air. Two reaction fronts were in situ observed during the oxidation of LCS, which was not found for AHSS. It was confirmed that the early detachment of LCS occurred after 30-s oxidation, however, the scale of AHSS maintained adherence due to the formation of a liquid phase. Besides, the scale thickness increased parabolically with oxidation time for both LCS and AHSS, with the estimated parabolic rate constants of 4.7 × 10−6 µm2/s and 4.9 × 10−6 µm2/s, respectively.

On specific features of oxidation of low-carbon steel in nitrate solutions

On specific features of oxidation of low-carbon steel in nitrate solutions

Two-step oxidation of steel in nitrate solutions

The possibility of increasing the thickness of a magnetite coating (MC) and its heterogeneity due to successive oxidation of low-carbon steel in two bathes based on ammonium nitrate solutions has been shown. Results are shown of a comparative corrosion test of steel with an MC obtained during single- or two-step oxidation in nitrate solutions, with further passivation by the IFKhAN-39U composition, which show the advantages of oxidation in two bathes.

Improvement of High Temperature Oxidation of Low Carbon Steel Exposed to Ethanol Combustion Product at 700 °C By Hot-Dip Aluminizing Coating

Low carbon steel (AISI 1005) was coated by hot-dipping into a molten Al-10% Si bath at 700 °C for 18s. After hotdipping treatment, the coating layers consisted of Al, Si, FeAl3, τ5-Fe2Al8Si, and Fe2Al5. The bare steel and the aluminized steel were isothermally oxidized at 700 °C in ethanol combustion product at atmospheric pressure for 49 h. The aluminized steel shows good performance in high temperature oxidation because the formation of Al2O3 layer on the coating surface. The growth of iron oxide nodules on the surface coating was accelerated by rapid outward diffusion of Fe-ions due to the presence of H2O-vapour generated by ethanol combustion. Thus, the oxidation rate of aluminized steel increased, resulting in a substantial mass-gain as the oxidation time increased. After longer exposure, the τ1(Al,Si)5Fe3 phase was completely transformed to the FeAl in the outer layer. The FeAl formed near the steel substrate was due to Fe-atoms diffusing into the Fe2Al5 layer when the time and temperature increased.

Temperature Effects on the Oxidation of Low Carbon Steel in N2–H2–H2O at 800–1200 °C

A low carbon, low silicon steel was reacted with flowing N2–H2–H2O gases at temperatures of 800–1,200 °C, to produce scales of fast-growing wustite, the only stable iron oxide under these conditions. Scaling kinetics were parabolic, after an initial period of linear reaction. The parabolic rate constants measured in the range 800–1,100 °C were two orders of magnitude lower than values predicted from Wagner’s diffusion theory, and activation energies were higher than expected. At 1,200 °C, however, the measured parabolic rate constant was in agreement with prediction. The initial period of linear kinetics was extensive at 1,100 °C, and rates are in agreement with those predicted for surface reaction rate control. Because the surface reaction is much less sensitive to temperature than the solid-state diffusion process, the extent of the linear kinetic regime is smaller at lower temperatures.

High-Temperature Oxidation of Low-Carbon Steel Coated by Solution-Spraying with Cerium and Aluminum Ions

Solutions containing cerium and aluminum ions were sprayed on a low-carbon steel, and high-temperature oxidation of the coated steels was examined. It is found that the oxidation rate was low, and removal of oxide scales was easy for the coated steels. These features were thought to be caused by the suppression of wüstite formation when the coating was applied.

On the possibility of reducing oxidation temperature of low-carbon steel in nitrate solutions

The effect of different additions on the protective properties of a magnetite coating prepared by the oxidation of low-carbon steel in nitrate solution at 70–98°C is studied using physical, electrochemical, and corrosion methods. The introduction of the developed addition URMP-5 to ammonium nitrate solution is shown to yield coatings with good protective properties, not only at 98°C, but also at 70°C. The further treatment of oxidized steel product with passivating compositions creates new fields for their using, even in the presence of direct atmospheric precipitations.

The influence of zinc cations on steel oxidation in nitrate solutions

The influence of zinc nitrate additives on the protective properties of the magnetite coating (MC) obtained by the oxidation of low-carbon steel in the nitrate solution at temperatures of 96–98°C has been studied by physical, electrochemical, and corrosion methods. It has been shown that, under these conditions, iron zinc spinel ZnFeO4, which is introduced into an MC, can be formed. Low concentrations (\( C_{Zn(NO_3 )_2 } \) = 25–150 mg/l) of it increase the corrosion stability of steel with MC in water containing chlorides and sulfates and also at the periodic moisture condensation of the sample surface. At \( C_{Zn(NO_3 )_2 } \) > 500 mg/l, MC formation stops.

Oxidation of Low-Carbon Steel in 17H2O-N2 at 900 °C

The oxidation kinetics of two low-carbon steels in a flowing 17H2O-N2 gas mixture at 900 °C and the scale structures developed are examined. Similar linear and parabolic oxidation kinetics are observed for the two steels, although some differences are observed within the first 5 minutes of oxidation and in the linear-to-parabolic transition period. The oxidation behaviors observed in the linear kinetics stage are more consistent with published results, exhibiting typical surface-reaction-controlled patterns. However, the observed parabolic oxidation rates are two orders of magnitude smaller than those of iron and steel oxidation in air and oxygen as well as that predicted using Wagner’s parabolic oxidation theory. Similar oxide scale structures are observed on the two steels for the samples oxidized for more than 15 minutes. The surfaces of the scales exhibit pyramidal, faceted grain structures with growth ledges developed on some crystal faces and growth pits at the peaks of the pyramidal grains. In their cross sections, the scales have a columnar structure and appear two layered, with a thin, outer magnetite layer and an inner, growing wustite layer. The wustite grains coarsen with increased oxidation time and develop a growth texture with preferred (111) and (110) orientations in parallel to the sample surface after oxidation for longer than 60 minutes. Conventional oxidation theories cannot provide a satisfactory explanation of the apparently conflicting results observed during the parabolic oxidation stage.

Surface oxidation of low carbon steel during laser treatment, its dependence on the initial microstructure and influence on the laser energy absorption

Laser treatment of steels in air is accompanied with formation of oxide layer on the surface. This leads to significant change of the absorption coefficient for the laser radiation and thus influences the temperature field in the material and the level of properties modification. By the methods of X-ray powder diffraction the parameters of the oxide films formed during surface laser treatment of sheet low carbon steels with Nd:glass pulsed laser have been investigated. The obtained experimental results show that the initial microstructure influences the parameters of the formed oxide films. The kinetics of the oxide film growth at the initial stages (within the laser pulse duration, 7 ms) has been simulated by the created computer codes based on the finite elements method. During the performed simulations the temperature dependencies of the thermal conductivity and specific heat capacity have been considered. The influence of the growing oxide film on the laser energy absorption has been analysed.

Oxidation of low carbon steel in multicomponent gases: Part I. Reaction mechanisms during isothermal oxidation

The article describes rates of oxidation of low carbon steel in various nitrogen-based atmospheres of O2, CO2, and H2O in the temperature range 800 °C to 1150 °C. In characterizing the oxidation process, the weight gains of the samples per unit surface area vs time data were analyzed. Reaction rates during oxidation in the binary atmospheres of CO2-N2 and H2O-N2 followed a linear rate law and were found to be proportional to the partial pressures of CO2 or H2O. These rates were controlled by rate of reactions at the oxide surface and were highly dependent on oxidation temperature. The activation energies of the phase boundary reactions obtained were approximately 274 and 264 kJ/mole, for oxidation in CO2 and H2O atmospheres, respectively. Oxidation in gases containing free oxygen showed that the main oxidizing agent was the free oxygen and that additions of CO2 and H2O had little effect on the magnitude of the initial oxidation rates. Experiments for oxidation in multicomponent gases showed that the overall oxidation rates were the additions of rates resulting from oxidation with the individual gaseous species O2, CO2, and H2O. Oxidation in these atmospheres exhibited an initial linear rate law which gradually transformed into a parabolic. Examination of scale microstructure after 1 hour of oxidation showed that, for oxidation in carbon dioxide and water vapor atmospheres, only wustite was present, while in atmospheres containing free oxygen, all three iron oxides, wustite, magnetite, and hematite, were present.

Oxidation of low carbon steel in multicomponent gases: Part II. Reaction mechanisms during reheating

Oxidation behavior of low carbon steel during reheating in an industrial walking-beam steel reheat furnace was investigated. It was observed that scaling (oxidation) rates were reduced by reducing the input air/fuel ratio to the furnace, thereby lowering concentrations of free oxygen in the combustion products from about 3 to 1.5 pct. Laboratory experiments involving isothermal and nonisothermal oxidation were carried out in atmospheres consisting of oxygen, carbon dioxide, water vapor, and nitrogen. A general equation for the prediction of weight gains due to oxidation during reheating, using isothermal oxidation rate constants, was developed. The prediction of weight gains from nonisothermal oxidation conducted in the laboratory was poor, owing to a separation of the scale from the metal substrate which took place at about 900 °C. The predicted weight gains during reheating in the industrial reheat furnace indicated that oxidation rates during reheating were intermediate between linear and parabolic, especially during reheating with high air/fuel ratio. However, the linear mechanism predominated. Laboratory isothermal experiments for oxidation in atmospheres containing free oxygen showed that the magnitude of the linear oxidation rates was determined by the oxygen concentration in the atmosphere. It was concluded that the observed reduction in scaling rates during reheating of low carbon steel in the industrial reheat furnace was a result of the lower free oxygen level in the furnace atmosphere.

The effect of oxygen concentration on the oxidation of low-carbon steel in the temperature range 1000 to 1250�C

This paper describes the oxidation behavior of low-carbon steel samples in binary gas mixtures of oxygen and nitrogen, at oxygen concentrations ranging between 1% and 15% and temperatures ranging between 1000 and 1250°C. Sample weight gains versus time were analyzed, along with measurements and calculations of sample heating rates due to exothermic heat of reaction at the sample surface. It was found that initial rates of oxidation depended on oxygen content in the gasmixture and that these reaction rates were linear up to oxide thicknesses of 0.4 to 0.5 mm. Calculations of linear oxidation rate constants based on equations for mass transport of oxygen in the gas mixture to the sample surface showed good agreement with those measured experimentally, indicating that the initial period of oxidation is controlled by the mass transport of oxygen to the reaction interface. The linear rate constants showed little dependency on temperature, an activation energy of approximately 17kJ/mole being obtained. Measurements of sample surface temperatures have shown that within this linear-oxidation regime, interfacial temperatures of the samples increase with increasing oxygen contents in the gas mixture, owing to exothermic heats of oxidation. Subsequent oxidation kinetics were found to be parabolic. Measured parabolic rates constants were in good agreement with previous investigations, with activation energy values of approximately 127kJ/mole.

Reducing the degree of oxidation of low-carbon steel

Reducing the degree of oxidation of low-carbon steel

Reduction in the state of oxidation of low-carbon steel from two-bath furnaces by adding coke breeze to the ladle

Reduction in the state of oxidation of low-carbon steel from two-bath furnaces by adding coke breeze to the ladle