Microstructure and Phase Identification of Tertiary Oxide Scale on Steel by EBSD

2009 ◽  
Vol 283-286 ◽  
pp. 419-424
Author(s):  
Lucia Suarez ◽  
Pablo Rodriguez-Calvillo ◽  
Rafael Colás ◽  
Yvan Houbaert
Keyword(s):  
Oxide Scale ◽  
Plane Strain ◽  
Oxide Layer ◽  
Hot Rolling ◽  
Protective Atmosphere ◽  
Phase Identification ◽  
Oxide Scales ◽  
Orientation Relationships ◽  
Complex Deformation ◽  
Ebsd Technique

Oxide scales growing during hot rolling of steel represent an industrial and environmental problem. Tertiary oxide, which starts to form before entering the finishing stands, remains on the steel surface until the end of the process, affecting the final surface quality and the response to downstream processing. Characterizing scale layers and the scale/steel interface in terms of phase morphology, texture, grain structure and chemical composition is fundamental for a better understanding of their behaviour and the effect of thermomechanical cycles on the material response to further processing. Thin tertiary scale layers have been grown on ULC steel under controlled conditions in a laboratory device adequately positioned in a compression-testing machine, immediately before plane strain deformation. After heating under a protective atmosphere (nitrogen), the samples have been oxidized in air at 1050°C for a short oxidation time. Immediately after this controlled oxidation, some of the samples were subjected to plane strain compression (PSC) inside the experimental device, in order to simulate the finishing hot rolling process. Direct observations of oxide scale layers are impossible. The EBSD technique has been identified as a powerful tool that can be used to reveal the microstructure within the oxide scale and to distinguish between its constitutive phases, based on their distinct crystal lattices. The texture of the deformed oxide scales, originally grown on ULC steel, was determined in a SEM using the EBSD technique. This will help to achieve a better understanding of their complex deformation behaviour. Because the substrate deformation affects the oxide layer, orientation relationships between scale layer and substrate were measured and the crystallographic orientation between undeformed and deformed areas was determined. Strongly textured wustite grains with a clearly pronounced columnar structure were observed after oxidation at 1050°C. The detailed EBSD study reveals that the oxide layer is able to accommodate a significant amount of deformation.

Texture Evolution of Tertiary Oxide Scale during Steel Plate Finishing Hot Rolling Simulation Tests

2007 ◽  
Vol 550 ◽  
pp. 557-562 ◽  
Author(s):  
Lucia Suarez ◽  
Roumen H. Petrov ◽  
Leo Kestens ◽  
M. Lamberigts ◽  
Yvan Houbaert
Keyword(s):  
Oxide Layer ◽  
Hot Rolling ◽  
Texture Evolution ◽  
Deformation Behaviour ◽  
Rolling Process ◽  
Columnar Structure ◽  
Protective Atmosphere ◽  
Orientation Relationships ◽  
Complex Deformation ◽  
Ebsd Technique

Thin tertiary scale layers have been grown on ULC steel specimens under controlled conditions. After heating under a protective atmosphere (nitrogen), the samples have been oxidised in air for various oxidation times at 1050°C. These experiments are considered a quantitatively and qualitatively reasonable simulation of the scale formation and growth occurring before hot rolling. Immediately after controlled oxidation, some of the samples were subjected to plane strain compression, in order to simulate the finishing hot rolling process. This approach provided a better insight into the deformation behaviour of the tertiary oxide layer in the first hot rolling pass. The layers produced were examined under the SEM using the EBSD technique for texture characterisation and phase morphology determination. The texture of the deformed oxide scales, originally grown on ULC steel at 1050°C, was determined in order to achieve a better understanding of their complex deformation behaviour. This paper gives a first approach of the study of deformed oxides by EBSD. Strongly textured wustite grains with a clearly pronounced columnar structure were observed after oxidation at 1050°C. As the substrate deformation probably affects the oxide layer, orientation relationships between scale layer and substrate were observed. The detailed EBSD study reveals that the oxide layer can accommodate a significant amount of deformation. The oxide layers exhibit good adhesion to the substrate and remain homogeneous over the thickness after compression.

Texture of Oxide Scales during Hot Rolling of Low Carbon Steel

2005 ◽  
Vol 495-497 ◽  
pp. 339-344 ◽  
Author(s):  
Vladimir V. Basabe ◽  
Jerzy A. Szpunar
Keyword(s):  
Carbon Steel ◽  
Oxide Scale ◽  
Hot Rolling ◽  
Low Carbon Steel ◽  
Cube Texture ◽  
Experimental Results ◽  
Oxide Scales ◽  
Low Carbon ◽  
Air Velocity ◽  
Temperature Range

The textures of oxide scales grown on low carbon steel in air over the temperature range 850-950°C were investigated. The low carbon steel was oxidized with the air velocity of 4.2 cm/s for 10 s in order to approximate the formation of tertiary scales in hot rolling. At 850°C, the wüstite texture and magnetite texture are weak with no dominant components. For the temperatures of 900 and 950°C, the wüstite and magnetite phases have a cube texture {001}<100>. The experimental results indicate that during hot rolling in the g region, the texture of the oxide scale is cubic and when rolling in the a region, the texture of the oxide scale is weak with no dominant components.

A Review of Microstructure and Microtexture of Tertiary Oxide Scale in a Hot Strip Mill

2016 ◽  
Vol 716 ◽  
pp. 843-855 ◽  
Author(s):  
Xiang Long Yu ◽  
Zheng Yi Jiang ◽  
Jing Wei Zhao ◽  
Dong Bin Wei ◽  
Ji Zhou
Keyword(s):  
Oxide Scale ◽  
Hot Rolling ◽  
Steel Substrate ◽  
Steel Strip ◽  
Oxidation Mechanism ◽  
Research Field ◽  
Experimental Investigations ◽  
Hot Strip Mill ◽  
Phase Identification ◽  
Microstructure And Microtexture

In hot rolling, metal oxides formed on steel surface can generally be classified as primary, secondary and tertiary oxide scales, corresponding to the reheating stages, the roughing stages and the finishing passes of continuous mills, respectively. The tertiary oxide scale grows into the final products on the hot-rolled steel strip during the finishing rolling and the subsequent cooling down to ambient temperature. We provide here a systematic overview of the oxidation mechanism, microstructure and microtexture development of the tertiary oxide scale. Mechanism of oxidation and Fe3O4 precipitation in tertiary oxide has been given as the fundamental theory. Three main sections has been divided in this review. The first section includes experimental investigations on microstructure evolution from the formation of oxide scale during hot rolling, then through continuous cooling, to Fe3O4 precipitation behaviour in storage cooling of hot-coiled strip. By using electron backscatter diffraction (EBSD) to characterise both the steel substrate and the oxide scale concurrently, the second section has further dealed with the texture-based analysis of oxide scale: phase identification, orientation analysis and coincident site lattice (CSL) boundaries. The third section has provided the general type of crystallographic texture and its evolutions in deformed Fe3O4 and steel substrate. Finally, the upcoming challenges have been addressed in this intriguing and promising research field.

Microstructure of Oxide Scale on Hot-Rolled Iron

2014 ◽  
Vol 922 ◽  
pp. 242-247 ◽  
Author(s):  
Kenichiro Hara ◽  
Hiroshi Utsunomiya ◽  
Ryo Matsumoto
Keyword(s):  
Oxide Scale ◽  
Hot Rolling ◽  
Surface Defects ◽  
Electron Backscatter Diffraction ◽  
Thickness Direction ◽  
Initial Stage ◽  
Columnar Grains ◽  
Ebsd Technique ◽  
Microscopic Deformation ◽  
Oxidation In Air

In hot rolling processes, oxide scale shows complicated deformation behavior and may cause surface defects on sheet. It influences the friction and the heat transfer on the interface between the sheet and the rolls. To reveal the mechanism, it is necessary to investigate the scale deformation during the hot rolling. In this study, the microstructure of the scale before / after the hot rolling was preserved by glass coating and analysed by scanning electron microscopy (SEM)/ electron backscatter diffraction (EBSD) technique. Using this technique, the microscopic deformation of oxide scale during hot rolling is discussed. Electrolytic pure iron sheets were rolled at a thickness reduction of 30% at 1273 K after oxidation in air for 0 s to 40 s. The scale consists of columnar grains which cover mostly throughout the thickness. The scale preferentially grows to the thickness direction at the initial stage of oxidation (<10 s). After the initial stage (>10 s), scale grains grow parallel as well as perpendicular in the thickness direction (ND). The scale grains are deformed at a fixed volume during hot rolling. The lower ductility of the thick scale results in the fracture of the scale and extrusion of matrix sheet to the outermost surface.

Effect of Mo on the Oxidation Behavior of NiTiAl Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 1481-1484
Author(s):  
Jian Xu ◽  
Xin Qing Zhao ◽  
Sheng Kai Gong
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
Oxide Layer ◽  
Oxygen Diffusion ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Oxide Scales ◽  
Cross Sectional ◽  
Oxidation Layer ◽  
Poor Adhesion

The effect of Mo on the oxidation behavior of TiNiAl at 1073K has been investigated. It is found that 1at.% Mo addition can increase the diffusion of Al in the alloys and promote the formation of dense and continuous Al-rich oxide layer. Therefore the oxygen diffusion can be effectively impeded and the oxidation behavior of TiNiAl is improved. The observation of the cross-sectional oxidation layer showed that beneath the top oxide scale a Mo-rich oxide layer formed. Because the oxide of Mo is volatile at high temperature, voids formed in the oxide scales during the oxidation process. 3at.% Mo addition could cause cracks between the oxide scale and the substrate, resulting in poor adhesion of the oxide scale to the substrate.

Surface Roughness and Friction in Hot Rolling of Stainless Steels

2014 ◽  
Vol 783-786 ◽  
pp. 795-800
Author(s):  
Zheng Yi Jiang ◽  
Dong Bin Wei ◽  
Xia Wei Cheng ◽  
X. Gao ◽  
J.W. Zhang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Experimental Method ◽  
Oxide Scale ◽  
Stainless Steels ◽  
Hot Rolling ◽  
Friction Condition ◽  
Average Thickness ◽  
Oxide Scales ◽  
Fem Model ◽  
Martensitic Stainless Steels

An experimental method was developed to examine oxidations of austenitic and martensitic stainless steels. The results show that the surface roughness along both rolling and transverse directions decreases with an increase of reduction. When the reheating time is increased, the average thickness of oxide scales of stainless steels increases, which results in relatively rough surface after hot rolling. The effects of oxide scale on the friction condition and surface roughness transfer in hot rolling depend on the oxide scale generated during reheating. The calculated surface roughness is close to the experimental results, which verifies the developed FEM model.

Tertiary Scale Behaviour during Finishing Hot Rolling of Steel Flat Products

2006 ◽  
Vol 15-17 ◽  
pp. 732-737 ◽  
Author(s):  
Lucia Suárez ◽  
G. Bourdon ◽  
X. Vanden Eynde ◽  
M. Lamberigts ◽  
Yvan Houbaert
Keyword(s):  
Plane Strain ◽  
Hot Rolling ◽  
Steel Strip ◽  
Plane Strain Compression ◽  
Protective Atmosphere ◽  
Hot Strip Mill ◽  
Test Machine ◽  
Scale Growth ◽  
Strip Surface ◽  
Oxide Layers

Steel strip surface oxidation during hot mill processing represents 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. Controlling the oxide layer growth kinetics and mechanical properties can make pickling easier and improve downstream behaviour. A thin wustite-dominated scale layer (<20 μm) is created under controlled conditions in an original laboratory device adequately positioned in a compression test machine to investigate plane strain compression. A first series of oxidation tests were performed on a ULC steel grade to measure the kinetics of oxide scale growth. The samples were first heated up under a protective atmosphere (nitrogen), before being oxidised in air at different temperatures for various oxidation times. These experiments can be considered fair quantitative and qualitative simulations of scale growth as it occurs in a hot strip mill, insofar as the results thus obtained are in good agreement with the literature. After the oxide growth, plane strain compression (PSC) was performed immediately to simulate the hot rolling process. The oxide layers were characterised before and after compression tests by optical and secondary electron microscopy. As expected, the oxide is seen to deform during compression. The obtained oxide layers exhibit good adhesion to the substrate and homogeneity over the thickness, even after compression.

Examination of Oxide Scales Formed During Hot Rolling of Steels

2019 ◽  
Vol 56 (7) ◽  
pp. 449-456
Author(s):  
T. Höfler ◽  
H. Danninger ◽  
B. Linder
Keyword(s):  
Hot Rolling ◽  
Oxide Scales

scholarly journals On the through-process texture evolution assessment in grain oriented Fe-3 wt% Si steel produced by a novel directional inoculation technique

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Snehashish Tripathy ◽  
Sandip Ghosh Chowdhury
Keyword(s):  
Magnetic Field ◽  
Hot Rolling ◽  
Texture Evolution ◽  
Lattice Parameter ◽  
Soft Magnetic ◽  
Oriented Growth ◽  
Inoculation Technique ◽  
Hot Band ◽  
Ebsd Technique ◽  
Cast Microstructure

AbstractA novel directional inoculation technique has been designed to cast thin slab ingots containing Goss (or near Goss) oriented components in the as cast microstructure under the combined effect of oriented nucleation and oriented growth. The same has been targeted so as to retain Goss orientations and simultaneously develop γ fiber components (ranging from {111}<$$1\overline{1}0$$ 1 1 ¯ 0 > to {111}<112>) during hot rolling. The designed scheme of directional inoculation achieved oriented nucleation by the effect of exogenously added soft magnetic inoculants under magnetic field and oriented growth by the effect of fast cooling rates prevailing in the mould. The choice of 65Fe–35Co (wt%) system as soft magnetic inoculants was made taking into account the similarity in crystal structure and lattice parameter. The chemically synthesized inoculants under the effect of external magnetic field during solidification were able to exhibit directional inoculation. Variation in the cast microstructure and microtexture by varying the extent of inoculant addition was studied by EBSD technique. The ingots cast under different conditions were subjected to a designed hot rolling schedule and the through process microstructural and microtextural evolution was assessed. It was observed that fine equiaxed grains with initial cube orientations in the as cast structure could lead to the most desirable microstructural as well as microtextural gradient in the hot band.

scholarly journals Analysis of oxide scale thickness and pores position of HCM12A steel in supercritical water

2021 ◽  
Vol 40 (1) ◽  
pp. 53-65
Author(s):  
Li Sun ◽  
Weiping Yan
Keyword(s):  
Diffusion Coefficient ◽  
Oxide Scale ◽  
Supercritical Water ◽  
Heating Surface ◽  
Oxidation Mechanism ◽  
Oxygen Activity ◽  
Oxide Scales ◽  
Spinel Layer ◽  
Magnetite Layer ◽  
Iron Diffusion

Abstract More attention has been paid to the exfoliation of oxide scale on high-temperature heating surface of utility boiler. The oxidation mechanism of HCM12A steel in supercritical water is proposed and the growth of oxide film is simulated. The duplex scale contains an outer magnetite layer and an inner Cr-rich spinel layer. According to the data of Backhaus and Töpfer, the diffusion coefficient values of iron in magnetite layer are discussed and the function of R V, R I {R}_{\text{I}} for oxygen activity can be used for calculation of iron diffusion coefficients in Cr-rich spinel layer. Based on Wagner’s oxidation theory, the oxidation rate constants of HCM12A are calculated at 500 and 600°C in supercritical water, compared with experimental data of the relevant literatures. The oxygen activities at the interfaces of alloy/Cr-rich spinel oxide and magnetite/supercritical water are estimated. The simulation results of weight gain are matched with the test data. The iron diffusion mechanisms inside the magnetite layer and the Cr-rich spinel layer are analyzed. The iron diffusion coefficient at the interface of Cr-rich spinel/magnetite is discontinuous, while the oxygen activity is continuous in the whole double layer. The thickness of oxide scale on inner tube walls of the final superheater coils (T91) of a 600 MW supercritical boiler is calculated by using the calculation method provided by the paper. The modeling results, the measured data, and the calculation results by the method are compared. Accurate calculation of the thickness of the inner and outer oxide scales can provide a necessary basis for predicting the stress and exfoliation of oxide scales.

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