Study on the High‐Temperature Evolution and Formation Mechanism of Inclusions in Te‐Treated Resulfurized Special Steel

Abstract

Te can effectively modify MnS inclusion to improve the anisotropy and machinability of steel. To figure out the mechanism of high‐temperature evolution and formation of inclusions, a high‐temperature confocal laser scanning microscope is used to in situ observe the performance of inclusions. In the steel with 22 ppm Te, Te mainly dissolves in MnS; no MnTe is generated. During the heating process, MnS inclusion remains solid state and no obvious phase change can be observed. In comparison, MnS–MnTe binary inclusion in the steel with 680 ppm Te forms a liquid phase due to the eutectic melting. The further increase of temperature causes the serious evaporation of Te. Based on scanning electron microscopy and energy‐dispersive spectrometry analysis and in situ observation of inclusions at high temperature, the formation mechanism of inclusions during solidification is proposed.

Tellurium Treatment for the Modification of Sulfide Inclusions and Corresponding Industrial Applications in Special Steels: A Review

“…[26] Copyright 2016, Elsevier. [57] Copyright 2021, John Wiley and Sons. Combined with the MnTe-MnS binary phase diagram, the precipitation rules of the MnTe-MnS composite inclusions at low and high Te contents were inferred by Shen et al, [23,57] and the schematic diagram is shown in Figure 7.…”

“…[57] Copyright 2021, John Wiley and Sons. Combined with the MnTe-MnS binary phase diagram, the precipitation rules of the MnTe-MnS composite inclusions at low and high Te contents were inferred by Shen et al, [23,57] and the schematic diagram is shown in Figure 7. When the Te content is low, in the liquid-phase solution formed by Mn, S, and Te, MnS preferentially precipitates and aggregates to form a large-sized MnS core.…”

“…Tien et al [ 22,23,28,56,57 ] obtained the heating and cooling data of the MnS‐MnTe system by differential thermal analysis (DTA) and plotted the binary phase diagram of MnS–MnTe with the obtained curves and parameters, as shown in Figure 3 . With a decrease in temperature, the metastable β‐MnTe precipitated at approximately 1,156 and at 1,030 °C, and it transformed into the stable α‐MnTe.…”

“…Schematic diagram of the formation of MnTe-MnS composite inclusions with different Te content during solidification process. Reproduced with permission [57]. Copyright 2021, John Wiley and Sons.…”

Effect of Permanent Magnet Stirring on Solidification of High‐Sulfur Micro‐Alloyed Steel under Different Magnetic Flux Densities

“…[1][2][3] Manganese sulfide (MnS) is a typical nonmetallic inclusion that can effectively improve the machinability of the sulfur-containing steel. [4,5] However, it can exert adverse effect on the performance of steel if the precipitation of MnS is controlled improperly. The coarse and aggregated MnS precipitates deform easily in the rolling process and lead to anisotropy and deterioration in mechanical properties of the steel.…”