Evolution of Desulfurization and Characterization of Inclusions in Dual Alloy Ingot Processed by Electroslag Remelting

Liu

et al. 2020

Metall. Res. Technol.

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The relationship of inclusions and primary carbides in H13 ingot processed by ESR with ANF-6 slag was investigated. It is found that inclusions in H13 ESR ingot are Al2O3, MnS and calcium-aluminate inclusions. The Al2O3 and MnS inclusions are found to be the nucleation cores of the primary carbides, whereas the calcium-aluminate inclusions are not. In order to study the effect of slag on inclusions and primary carbides of H13 steel further, the characteristics of inclusions and primary carbides in steel remelted by ANF-6 and ANF-8 slags were analyzed, and compared to the steel remelted without slag. After being remelted with the ANF-6 (70 mass% CaF2 + 30 mass% Al2O3) and ANF-8 (60 mass% CaF2 + 20 mass% CaO + 20 mass% Al2O3) slags, Al2O3 and CaO contents in calcium-aluminate inclusions increase, respectively. The ANF-8 slag shows stronger desulfurization ability than ANF-6 slag, which contributes to the delay of MnS inclusions precipitation and the decrease of inclusion number, and finally helps to inhibit the precipitation of primary carbides. It implies that the ANF-8 is the promising slag for the ESR process of H13 steel.

Section: Precipitation Of the Mns Inclusionsmentioning

confidence: 99%

Role of slag on inclusions control and its effect on primary carbides in H13 steel

Liu

et al. 2020

Metall. Res. Technol.

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“…The actual solubility product of Mn and S changing with solid fraction in electrode and remelted ingot were calculated by Eqs. (5)- (12). The temperature at each solid fraction during solidification process and the corresponding equilibrium solubility product of Mn and S are also calculated, the results are shown in Fig.…”

Section: (12)mentioning

confidence: 99%

Formation and Evolution of Non-Metallic Inclusions in Calcium Treatment H13 Steel during Electroslag Remelting Process

Shi

et al. 2019

ISIJ Int.

In the current study, the evolution of inclusions in H13 steel electrode with different Ca content refined through ESR process were analyzed, the formation and evolution of sulfide and oxide inclusions during ESR process was determined based on experiments and thermodynamic calculation. The results showed: The inclusions of remelted ingot were Al 2 O 3 , CaO-Al 2 O 3-CaS and CaO-Al 2 O 3-MgO-CaS, more than half of the total inclusions were smaller than 3 μm. The cleanliness and inclusions of remelted ingot had no difference with different Ca content in electrode. MnS inclusions in electrode precipitated while the solid fraction reached 0.98. MnS inclusions cannot precipitate due to the low level of S content in remelted ingot and the decrease of Mn and S segregation on the front edge of solidified shell. The low-meltingtemperature inclusions were dissolved and disappeared completely before liquid metal droplets collected in the liquid metal pool. The different of local cooling intensity during ESR process and high Al 2 O 3 content of liquid inclusion in molten pool promoted the formation of large amount of tiny Al 2 O 3 inclusions in remelted ingot.

“…The values of the interaction coefficients of activity at 1873 K are collected from [25]. T is the temperature of solidification front and can be expressed as [26]:…”

Section: Vc Mo 2 C Al 2 O 3 Mnsmentioning

confidence: 99%

Investigation of Primary Carbides in a Commercial-Sized Electroslag Remelting Ingot of H13 Steel

Liu

et al. 2019

Metals

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The characteristics of primary carbides in a commercial-sized (one ton) electroslag remelting (ESR) ingot of AISI H13 steel were investigated. The interaction between the primary carbides and inclusions was also clarified. The results indicate that there are two types of primary carbides, V-rich and Mo-rich primary carbides, in the H13 ESR ingot. The quantity, the area fraction, and the size of the two primary carbides tend to decrease from the center of the H13 ESR ingot to the outer surface. Additionally, the V-rich primary carbide is obviously larger than the Mo-rich primary carbide. The Al 2 O 3 inclusion can promote the precipitation of the V-rich primary carbide, while the MnS inclusion encourages the precipitation of Mo-rich primary carbide. The CaO·Al 2 O 3 inclusion cannot act as the nucleation site for the precipitation of the two primary carbides. The solid fraction that the V-rich primary carbide begins to precipitate ranges from 0.965 to 0.983, and that for the Mo-rich primary carbide and the MnS inclusion change from 0.9990 to 0.9998 and from 0.989 to 0.990, respectively.