Transformation of Oxide Inclusions in Type 304 Stainless Steels during Heat Treatment

Ren, Ying; Zhang, Lifeng; Pistorius, Petrus Christiaan

doi:10.1007/s11663-017-1007-8

Cited by 82 publications

(57 citation statements)

References 49 publications

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“…Solid-state interfacial reaction between some oxide inclusions and steel matrix could occur during heat treatment. This has been confirmed in 18 mass% Cr-8 mass% Ni stainless steel [14][15][16][17][18]. In this study, the same transformation was also observed in both steels #1 and #2.…”

Section: Interfacial Reaction Between Inclusions and Steel Matrixsupporting

confidence: 83%

“…This is practically important because steel quality significantly depends on the final state of inclusions after different thermal and mechanical treatments [13]. Many researchers have reported that some inclusions would change during heat treatment [14][15][16][17][18][19][20][21]. In 18 mass% Cr-8 mass% Ni austenitic stainless steel, MnO-SiO 2 oxide inclusions changed to finer MnO-Cr 2 O 3 spinel during heat treatment at 1473 K due to the interfacial reaction between inclusions and steel matrix [14][15][16][17][18].…”

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confidence: 99%

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

Zhang

Yang

et al. 2019

Metals

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To provide fundamental information on the control of rare earth inclusions in solid steel, two 18 mass% Cr-8 mass% Ni stainless steels with different yttrium additions were prepared using an electric resistance furnace and the evolution of yttrium-based oxide inclusions during heat treatment of the steels at 1473 K was investigated. In both as-cast steels, homogeneous spherical Al-Y-Si(-Mn-Cr) oxide inclusions were observed; however, the steel with larger yttrium additions also had some heterogeneous oxide inclusions with double phases. After heating, a new oxide phase with higher yttrium content precipitated from the original inclusions and resulted in partitioning to Y-rich and Al-rich parts in both steels. The average size and number density of inclusions slightly increased, and the morphology of inclusions changed from spherical to irregular. The transformation mechanism during isothermal heating was proposed to be the mutual effects of (i) internal transformation of the yttrium-based inclusions owing to crystallization of glassy oxide and (ii) interfacial reaction between inclusions and the steel matrix.Metals 2019, 9, 961 2 of 15 morphology of inclusions changed from dendritic to globular. A similar result was also observed by Katsumata et al. in 25 mass% Cr-6 mass% Ni stainless steel [8]. Kwon et al. [9,10] investigated the evolution of inclusions in Al-killed stainless steel with Ce addition at 1873 K. Mn(Cr)-silicates were found to be the primary inclusions before Al addition. When Al was added without Ce addition, the initial Mn(Cr)-silicate changed to Al 2 O 3 -rich inclusions. Then, Al-Ce complex inclusions were formed in the steel after Ce addition due to the reaction between Ce and Al 2 O 3 particles. Jönsson et al. [11,12] investigated the three-dimensional characteristics of clusters in REM-alloyed (Ce, La, Pr, and Nd) stainless steel through an electrolytic extraction method. It was found that most of the REM cluster consisted of regular and irregular REM-oxides, and the size of these clusters varied in the range of 2 to 23 µm. Moreover, turbulent collisions were determined to be the dominant form for the growth of REM clusters. With increasing the size of clusters, the growth rate of REM clusters increased.The changing behavior of rare earth inclusions in molten steel is relatively clear now; however, less attention has been paid to the possible transformation of rare earth inclusions in solid steel during heat treatment. This is practically important because steel quality significantly depends on the final state of inclusions after different thermal and mechanical treatments [13]. Many researchers have reported that some inclusions would change during heat treatment [14][15][16][17][18][19][20][21]. In 18 mass% Cr-8 mass% Ni austenitic stainless steel, MnO-SiO 2 oxide inclusions changed to finer MnO-Cr 2 O 3 spinel during heat treatment at 1473 K due to the interfacial reaction between inclusions and steel matrix [14][15][16][17][18]. Grain growth during heat treatment was also suppressed effec...

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Section: Interfacial Reaction Between Inclusions and Steel Matrixsupporting

confidence: 83%

mentioning

confidence: 99%

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

Zhang

Yang

et al. 2019

Metals

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“…Based on Ren's research, the MnCr 2 O 4 phase in the inclusions of 304 stainless steel was precipitated at the temperature lower than 1350 °C, at which the steel has been completely solidified. There should be little Cr 2 O 3 formed in inclusions during solidification.…”

Section: Inclusion Characteristics Under Different Cooling Ratementioning

confidence: 99%

“…In this stage, the cooling rate might affect the composition, size, and number of inclusions. The second step was the transformation of inclusions into the MnO‐Cr 2 O 3 ‐Al 2 O 3 system in solid steel by the interaction between inclusions and the steel matrix when the temperature decreased to the formation temperature of MnO‐Cr 2 O 3 (

T_{true({MnO‐Cr}_{2} {normalO}_{3} true)}

in the figure, was around 1310 °C according to Ren's calculation) . Reactions (5) and (7) were supposed to carry out at this step under the cooling rate larger than 30 and of 0.16 K s −1 , respectively.…”

Section: Inclusion Characteristics Under Different Cooling Ratementioning

confidence: 99%

“…The formation, removal, and modification of inclusions in molten steel have been widely investigated. Meanwhile, the changes of inclusions in solid steel during heat treatment have been paid more and more attention to, especially for stainless steels . The evolution of inclusions during the solidification of carbon steels has also been well studied .…”

Section: Introductionmentioning

confidence: 99%

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Effect of Cooling Rate on Oxide Inclusions During Solidification of 304 Stainless Steel

Wang

Yang

Zhang

2019

steel research int.

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Laboratory experiments are carried out to investigate the effect of cooling rate on oxide inclusions during the solidification of Si-Mn killed 304 stainless steel. The oxide inclusions in the 304 stainless steel were Al 2 O 3 -SiO 2 -CaO-MnO-MgO system. During the cooling process, the change of inclusions is supposed to consist of two steps. The first step is the precipitation and growth of SiO 2 -MnO-Al 2 O 3 type inclusions during the solidification process of steel. The second step is the transformation of inclusions into the MnO-Cr 2 O 3 -Al 2 O 3 system in solid steel by the interaction between inclusions and the steel matrix. Smaller cooling rate led to the more complete growth and transformation of inclusions. With decreasing the cooling rate, the number of large inclusions increased while that of small inclusions decreased. Meanwhile, the diameter of the inclusions increased. The main reason for the size difference of inclusions at different cooling rates is the difference of inclusion growth during solidification.

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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 Type 304 Stainless Steels during Heat Treatment

Cited by 82 publications

References 49 publications

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

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

Effect of Cooling Rate on Oxide Inclusions During Solidification of 304 Stainless Steel

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

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