Transformation of Oxide Inclusions in Stainless Steel Containing Yttrium during Isothermal Heating at 1473 K

Zhang, Xueliang; Yang, Shufeng; Li, Jingshe; Jin-qiang, WU

doi:10.3390/met9090961

Cited by 10 publications

(6 citation statements)

References 37 publications

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“…silica) caused by fast diffusion and chemical reaction. The high quantity of inclusions in Billet 2 accelerated the element concentration and facilitated the formation of new inclusions [44][45][46]. The large-sized inclusions facilitated crack initiation, while the large volume fraction of inclusions accelerated the crack propagation along the grain boundary.…”

Section: Fracture Mechanisms In Cwrmentioning

confidence: 99%

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

et al. 2020

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Central cracking in cross-wedge-rolled workpieces results in high wastage and economic loss. Recent cross-wedge rolling tests on two batches of steel showed that one batch formed central cracks, while the other was crack-free. The batches were both nominally of the same chemical composition and thermomechanical treatment history. In addition, both batches had passed all the standard quality assessments set for conventional forging processes. It was suspected that the different cracking behaviours were due to differences in microstructure between the two as-received steel billets, and the material in cross-wedge rolling (CWR) was more sensitive to the initial microstructure compared with other forging processes due to its specific loading condition including ostensibly compression and large plastic strain. Nevertheless, no previous study of this important problem could be identified. The aim of this study is, therefore, to identify the key microstructural features determining the central crack formation behaviour in CWR. The hot workability of the as-received billets was studied under uniaxial tensile conditions using a Gleeble 3800 test machine. Scanning electron microscope with energy-dispersive X-ray spectroscopy and electron backscatter diffraction was applied to characterise, quantitatively analyse, and compare the chemical composition, phase, grain, and inclusions in these two billets, both at room temperature and also at the CWR temperature (1080°C). Non-metallic inclusions (oxides, sulphides, and silicates) in the billets were determined to be the main cause of the reported central cracking problem. The ductility of the steels at both room and elevated temperatures deteriorated markedly in the presence of the large volumes of inclusions. Grain boundary embrittlement occurred at the CWR temperature due to the aggregation of inclusions along the grain boundaries. It is suggested that a standard on specifying the inclusion quantity and size in CWR billets be established to produce crack-free products.

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Section: Fracture Mechanisms In Cwrmentioning

confidence: 99%

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

et al. 2020

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“…When the steel samples went through isothermal heating at 1473 K (1200 °C) for 1, 3, 5, and 10 h, changes in the average size and chemical composition of inclusion likely resulted from the solid‐state interfacial reactions between the steel and inclusions. [ 25–27 ]…”

Section: Resultsmentioning

confidence: 99%

“…As such, the types of inclusion that are most detrimental to linepipe steel (large and elongated inclusions) were effectively suppressed. Zhang et al [ 26 ] investigated the effect of yttrium on the modification of oxide inclusions in 304 stainless steels during isothermal heating at 1473 K (1200 °C). A new Y‐rich oxide phase was found to precipitate in the initial Al‐rich inclusions after the heating.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic and Kinetic Analyses of Inclusion Transformations in Linepipe Steel during Isothermal Heating at 1473 K (1200 °C)

Liu

Webler

2022

steel research int.

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Understanding the thermodynamics and kinetics of solid‐state reactions on the characteristic transformations of nonmetallic inclusions in the linepipe steel during isothermal heating is of great importance for achieving good steel quality. Herein, heat treatment experiments are used, which are carried out at 1473 K (1200 °C) between 1 and 10 h in an Ar atmosphere, to investigate the resulting changes in the inclusion characteristics of linepipe steel. The chemical compositions, morphology, and size distribution of the inclusions are characterized. Results indicate that Mn and S in the linepipe steel react with CaS inclusions/phases to form (Ca, Mn)S inclusions/phases during heating at 1473 K (1200 °C), while MnS inclusions are gradually decomposed. Based on the FactSage Macro process, a kinetic model is established to calculate the regional equilibrium at the interface between the inclusion and steel at every time step and predict the extent of the inclusion transformation during isothermal heating. The experimental measurements and predicted results are in reasonable agreement. The diffusion‐limited kinetic model verifies that the effects of heating time and inclusion size on inclusion transformation are as predicted for Mn and S diffusion control by observation.

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“…The deformation of inclusions is related to the friction between inclusions and steel matrix. [29][30][31][32] Compared with spherical inclusions, the specific surface area of irregular inclusions obviously increased, and the contact area between the inclusions and the alloy matrix was large, but the connection between inclusions was weak. During the warm rolling process, the inclusions would bear greater stress and would be more likely to fracture.…”

Section: Evolution Mechanism Of Oxide Inclusions During Warm Rolling ...mentioning

confidence: 99%

Evolution Behaviors of Inclusions in Warm‐Rolled L605 Thin‐Walled Tubes and Their Effects on Machinability

Xun,

Luo,

et al. 2023

Adv Eng Mater

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This paper investigates the evolution behaviors of inclusions in the warm rolling process of L605 thin‐walled tubes and analyzes their influencing mechanism. Homogeneous spherical and irregular SiO2–Al2O3–Cr2O3(MnO + CaO) inclusions are observed in the cast tubes. After warm rolling, the homogeneous inclusions are changed into heterogeneous spherical ones with gray‐colored (Al2O3)‐rich phase and dark‐colored (SiO2)‐rich phase and Cr2O3(MnO + CaO)‐rich phase due to different deformability of various inclusions under the combined effects of diameter reduction and wall pressure. As the rolling times of tubes increases, large‐sized inclusions are crushed continuously, and the average size of the inclusions gradually decreases. At the same time, the number density of inclusions presents a first increasing and then decreasing trend. It is estimated that the critical size of the inclusions that are hard to further crack in warm rolling is about 0.5 μm. Meanwhile, the inclusions would lead to stress concentration at the positions near large‐sized irregular inclusions, causing cracks and penetrating defects. The simulation results show that the stress near the outer diameter of the inclusions is twice that in the middle and the changes of stress in the 30 μm inclusions and nearby areas exhibit a significant increase compared to the small‐sized 2 μm inclusions.

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Transformation of Oxide Inclusions in Stainless Steel Containing Yttrium during Isothermal Heating at 1473 K

Cited by 10 publications

References 37 publications

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

Thermodynamic and Kinetic Analyses of Inclusion Transformations in Linepipe Steel during Isothermal Heating at 1473 K (1200 °C)

Evolution Behaviors of Inclusions in Warm‐Rolled L605 Thin‐Walled Tubes and Their Effects on Machinability

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