Effect of a grain-refined microalloyed steel substrate on the formation mechanism of a tight oxide scale

Surface and Coatings Technology

et al. 2015

Self Cite

Q. (2015). Dependence of texture development on the grain size of tertiary oxide scales formed on a microalloyed steel. Surface and Coatings Technology, Dependence of texture development on the grain size of tertiary oxide scales formed on a microalloyed steel AbstractBoth orientational and geometrical characteristics of grains in tertiary oxide scales have been quantitatively investigated using the electron backscatter diffraction (EBSD) technique. Phase and orientation mappings demonstrate that the {001} planes of magnetite and the {0001} planes of hematite are parallel to the direction of oxide growth. Pole figures (PFs) as scattering plots clearly display the direct correlation between the orientations and microstructure sites of magnetite grains. Magnetite grains develop a strong rotated cube texture component that shifts to the {100} component, whereas those with the grain size of 1-5. μm develop the {001} cube texture component. The refined magnetite grains surrounding the abnormal ones can be a combined process, including magnetite pro-eutectoid during hot rolling and cooling and re-oxidation during air-cooling. Our findings offer insights toward further understanding of the link between the geometrical and orientation parameters of grains with respect to the deformation behaviour of oxide scales formed at elevated temperatures.

Section: Characterising Grain Sizesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dependence of texture development on the grain size of tertiary oxide scales formed on a microalloyed steel

Surface and Coatings Technology

et al. 2015

Self Cite

“…1c). Details of the grain size associated with the steel substrate can be found in our previous study [42]. …”

Section: Grain Reconstructionmentioning

confidence: 99%

Effects of grain boundaries in oxide scale on tribological properties of nanoparticles lubrication

et al. 2015

Wear

Self Cite

The characters of grain boundaries in oxide layers formed on substrates influence adhesion and friction behaviour, surface fracture and wear during high temperature steel processing. In this work, an electron backscattered diffraction (EBSD) analysis was conducted to investigate the role of surface grain boundary and orientation in magnetite (Fe 3 O 4 )/haematite (α-Fe 2 O 3 ) scale during hot rolling, and further evaluate their effects on tribological properties of water-based nanoparticles lubrication. The results demonstrate that Fe 3 O 4 (100) plane is strongly sensitive to the surface characteristics as the minimisation of surface energy. Coincident site lattice (CSL) boundaries in microstructure is in presence of Σ3 in the Fe 3 O 4 and Σ13b in the Fe 2 O 3 of the substrates subjected to a thickness reduction of 28% and cooling rate of 28 ° C/s. This is due in great part to the changes in crystal slip systems. These low-Σ CSL boundaries in oxide scale offer obstacles to the propagation of cracks, where some of nanoparticles collected would be trapped at the interface and thereby may cause high wear rates. A lubrication mechanism is proposed to explain the grain boundary effect on nanoparticles lubrication, and further to determine the dependence of frictional behaviour on surface energy, crystallographic preferred orientation (microtexture) and crystal structure. These results provide an intriguing new insight into the application of water-based lubricant with graphite nanoparticles. AbstractThe characters of grain boundaries in oxide layers formed on substrates influence adhesion and friction behaviour, surface fracture and wear during high temperature steel processing. In this work, a thickness reduction of 28% and cooling rate of 28 °C/s. This is due in great part to the changes in crystal slip systems. These low-Σ CSL boundaries in oxide scale offer obstacles to the propagation of cracks, where some of nanoparticles collected would be trapped at the interface and thereby may cause high wear rates. A lubrication mechanism is proposed to explain the grain boundary effect on nanoparticles lubrication, and further to determine the dependence of frictional behaviour on surface energy, crystallographic preferred orientation (microtexture) and crystal structure. These results provide an intriguing new insight into the application of water-based lubricant with graphite nanoparticles.

“…In most cases, a multi-layered oxide scale formed on a steel at high temperature consists of a thin [5,6]. By contrast, the tertiary oxide scale at room temperature comprises mainly Fe 3 O 4 and α-Fe 2 O 3 because the unstable FeO will decompose into Fe 3 O 4 and ferrite (α-Fe) below the eutectoid temperature of FeO at 570 °C [7,8].…”

Section: Introductionmentioning

confidence: 99%

Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD

Surface and Coatings Technology

et al. 2015

Self Cite

Q. (2015). Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD. Surface and Coatings Technology, Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD AbstractThis work presents a fine microstructure and local misorientation study of various oxide phases in the tertiary oxide scale formed on a hot-rolled steel strip via electron back-scattering diffraction (EBSD). Local strain in individual grains of four phases, ferrite (α-Fe), wustite (FeO), magnetite (Fe 3 O 4 ) and hematite (α-Fe 2 O 3 ), has been systematically analysed. The results reveal that Fe 3 O 4 has a lower local strain than α-Fe 2 O 3 , in particular, on the surface and inner layers of the oxide scale. The multiphase oxides along the cracking or α-Fe 2 O 3 penetration generally develop a high local misorientation. Localised stain along the cracks demonstrates that the misorientation tends to be strong near grain boundaries. The high fraction of small Fe 3 O 4 grains accumulate at the oxide-substrate interface, which leads to a dramatic increase in the intensity of local stain. This variation is due mainly to the phase transformation among the oxide phases, i.e., the Fe 3 O 4 particles during their nucleation and growth. The combined action of stress relief and re-oxidisation is proposed to explain the formation of Fe 3 O 4 seam at the oxide-steel interface. The present study offers an intriguing insight into the deformation behaviour of the tertiary oxide scale formed on steels, and may help with understanding the stress-aided oxidation effect of metal alloys. offers an intriguing insight into the deformation behaviour of the tertiary oxide scale formed on steels, and may help with understanding the stress-aided oxidation effect of metal alloys.