Grain Boundary in Oxide Scale During High-Temperature Metal Processing

Yu, Xianglong; Zhou, Ji

doi:10.5772/66211

Cited by 10 publications

(14 citation statements)

References 34 publications

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“…32,33 The needed activation energies of diffusion via the grain boundary and dislocation are smaller than that of lattice diffusion. 34 A high vacancy concentration and various defects of grain boundaries and dislocations contribute to the diffusion of Mn. In the steel base, these defect areas include the grain boundaries, dislocations, and point defects.…”

Section: Discussionmentioning

confidence: 99%

“…Dwarapudi and Ranjan indicated that the melted phase would wet the solid surface and enhance the diffusion through the defects (atom-vacancy and atom-interstitial coupling). The vacancy defects are preferentially occupied by Mn because of the higher binding energy between the vacancies and Mn. , The needed activation energies of diffusion via the grain boundary and dislocation are smaller than that of lattice diffusion . A high vacancy concentration and various defects of grain boundaries and dislocations contribute to the diffusion of Mn.…”

Section: Discussionmentioning

confidence: 99%

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Contribution of Sodium Metasilicate to the Diffusion of Mn in Steel under Tribological Contact at High Temperatures

et al. 2019

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The environmentally friendly sodium metasilicate is regarded as one of the promising lubricants for hot metal formation because of its excellent thermal stability and unique physical chemistry property. This work aims to reveal how alkaline silicate reacts with manganese (Mn) in mild steel during tribological contact at high temperatures. The results suggest that the melted sodium metasilicate contributes to the diffusion of Mn from mild steel because of the combined effects of the chemical potential gradient and the different oxidation states of Mn in the steel substrate and melts. The hierarchical structure of the tribo-interface indicates that a Mn-rich layer containing fingerlike and mushroomlike oxides, such as Mn 2 O 3 , NaMnO 2 , and MnFe 2 O 4 , exists between the iron oxide scale and the sodium-rich layer, which acts as a barrier to the inward diffusion of oxygen.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Contribution of Sodium Metasilicate to the Diffusion of Mn in Steel under Tribological Contact at High Temperatures

et al. 2019

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“…As compared to those observed by Kondo and Tanei [41], Yates et al, [71], Yanagihara et al, [34] and Yu et al, [69] observed more on the microstructure and morphologies of oxide growth on the typical steel substrate as indicated in Figure 1. As shown in Figure 1(a) and (b) Electron backscattered diffraction (EBSD) phase mapping showing a columnar-shape microstructure at the region between the outer granular grains and the globular inner layers.…”

Section: Oxide Layer Propertiesmentioning

confidence: 49%

Selective Oxide Deposition on Fe-Based Alloys in Dry High Temperature Environment – A Review

Hussin¹,

Lah²

2020

ARFMTS

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This paper presents a review of an investigation on selective deposition of oxides on Fe-based alloys in dry high temperature environment. The oxidation reaction occurred in order to promote a protective oxide layer to prevent corrosion attack and secure the metal substrate from degrade further. As temperature increased, the oxidation rate was significantly increased. Selective oxidation of an alloy component significantly lowers the concentration of that particular metal element in the alloy subsurface zones. As the cyclic thermal conditions increases, associated mechanical damage to the oxide scale leads to the porous oxide growth and also accelerates the depletion of alloy element. Eventually, prolong the process a point is reached where diffusion of anion to the alloy becomes competitive with the outward diffusion of metal cation to the developed protective scale. Selective oxidation changes the mechanical properties mainly due to the grain boundary oxidation. It is considered a short-path circuit for diffusion and hence leads to weaken the cohesive strength of individual grains. The focus of this work is to review the complex oxidation process due to the occurrence of selective oxidation and oxide deposition with the growth of oxide scale at different rates and also due to the presence of defects and clear microstructure differences of Fe -based alloys. It is also to enhance basic knowledge regarding the oxide layer behaviour that requires an understanding of alloy composition and microstructure. The consequences of oxide growth are specifically relative to the effects of factors such as exposure duration, temperature and operating parameters that must be clearly understood.

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“…Generally, too much energy input causes spatter and fume ejection during the SLM process, leading to a porous microstructure. The diffusion of metal ions can also produce cavities to facilitate the formation of local pores and vacancies (Yu and Zhou, 2017; Wang et al , 2020b). Vaporization becomes extreme whenever the surface temperature of the molten pool exceeds the material's boiling point of powder.…”

Section: Resultsmentioning

confidence: 99%

The influence of laser power and scanning speed on the microstructure and surface morphology of Cu2O parts in SLM

Ullah

Rehman

Salamcı

et al. 2022

RPJ

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Purpose This paper aims to reduce part defects and improve ceramic additive manufacturing (AM). Selective laser melting (SLM) experiments were carried out to explore the effect of laser power and scanning speed on the microstructure, melting behaviour and surface roughness of cuprous oxide (Cu2O) ceramic. Design/methodology/approach The experiments were designed based on varying laser power and scanning speed. The laser power was changed between 50 W and 140 W, and the scanning speed was changed between 170 mm/s and 210 mm/s. Other parameters, such as scanning strategy, layer thickness and hatch spacing, remain constant. Findings Laser power and scan speed are the two important laser parameters of great significance in the SLM technique that directly affect the molten state of ceramic powders. The findings reveal that Cu2O part defects are widely controlled by gradually increasing the laser power to 110 W and reducing the scanning speed to 170 mm/s. Furthermore, excessive laser power (>120 W) caused surface roughness, cavities and porous microstructure due to the extremely high energy input of the laser beam. Originality/value The SLM technique was used to produce Cu2O ceramic specimens. SLM of oxide ceramic became feasible using a slurry-based approach. The causes of several part defects such as spattering effect, crack initiation and propagation, the formation of porous microstructure, surface roughness and asymmetrical grain growth during the SLM of cuprous oxide (Cu2O) are thoroughly investigated.

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Grain Boundary in Oxide Scale During High-Temperature Metal Processing

Cited by 10 publications

References 34 publications

Contribution of Sodium Metasilicate to the Diffusion of Mn in Steel under Tribological Contact at High Temperatures

Contribution of Sodium Metasilicate to the Diffusion of Mn in Steel under Tribological Contact at High Temperatures

Selective Oxide Deposition on Fe-Based Alloys in Dry High Temperature Environment – A Review

The influence of laser power and scanning speed on the microstructure and surface morphology of Cu2O parts in SLM

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