This article reports the morphology, size, and distribution evolution of MnS inclusions in non-quenched and tempered steel during heat treatment. The variation of single large-sized MnS inclusions at high temperature ...This article reports the morphology, size, and distribution evolution of MnS inclusions in non-quenched and tempered steel during heat treatment. The variation of single large-sized MnS inclusions at high temperature was observed in situ using a confocal scanning laser microscope （CSLM）. The slender MnS inclusions first changed to pearl-like slrings. These small-sized pearls subsequently coalesced and became closer together as the temperature increased. Large-sized MnS inclusions in non-quenched and tempered steel samples with different thermal histories were investigated with respect to the evolution of their morphology, size, and distribution. After 30 min of ovulation at 1573 K, the percentage of MnS inclusions larger than 3 μm decreased from 50.5% to 3.0%. After a 3 h making period, Ostwald ripening occurred. Most MnS inclusions moved from the grain bounda- ries to the interior. The present study demonstrates that heat treatment is an effective method of changing the morphology, size, and distribution of MnS inclusions, especially large-sized ones.展开更多
The behaviors of typical iron ores at high temperature were observed by confocal scanning laser microscopy. Four critical temperature points and liquid flow velocity at high temperatures of iron ores were obtained and...The behaviors of typical iron ores at high temperature were observed by confocal scanning laser microscopy. Four critical temperature points and liquid flow velocity at high temperatures of iron ores were obtained and the temperature points contain temperature at which sample starts to shrink, temperature at which the initial liquid phase forms, temperature at which a lot of liquid forms and temperature at which liquid consolidation ends. Under the same CaO to Fe203 ratio, the liquid phase fluidity of iron ore fines of Carajas （IOC） is good. However, under the same basicity, as the content of SiO2 in IOC is low, the liquid phase fluidity of IOC is much smaller than that of Yandi fine. After analysis of the initial formation and development of the liquid phase and the final consolidation process, the high-temperature process evaluation system （HTPES for short） of iron ore was established. The idea of ＂dense ore matching fusible ore＂ instead of ＂relatively fusible ore＂ was proposed based on the results of HTPES and applied in ore matching of a sinter plant from Shougang Jingtang. The use of IOC （13-18%） instead of standard sintering fines （SSF） improved liquid phase fluidity and ensured the sinter quality. Furthermore, the use of IOC fine （18-23%） with Hainan fine （0-2%） instead of SSF, a mixture of hematite and Marra Mamba ore and concentrates guaranteed the quality of sinter ore through improving fluidity, in the meantime reducing ore matching costs. With the establishment and application of HTPES, the sinter plant has achieved good economic benefits under the premise of ensuring the quality of sinter ore.展开更多
文摘This article reports the morphology, size, and distribution evolution of MnS inclusions in non-quenched and tempered steel during heat treatment. The variation of single large-sized MnS inclusions at high temperature was observed in situ using a confocal scanning laser microscope （CSLM）. The slender MnS inclusions first changed to pearl-like slrings. These small-sized pearls subsequently coalesced and became closer together as the temperature increased. Large-sized MnS inclusions in non-quenched and tempered steel samples with different thermal histories were investigated with respect to the evolution of their morphology, size, and distribution. After 30 min of ovulation at 1573 K, the percentage of MnS inclusions larger than 3 μm decreased from 50.5% to 3.0%. After a 3 h making period, Ostwald ripening occurred. Most MnS inclusions moved from the grain bounda- ries to the interior. The present study demonstrates that heat treatment is an effective method of changing the morphology, size, and distribution of MnS inclusions, especially large-sized ones.
文摘The behaviors of typical iron ores at high temperature were observed by confocal scanning laser microscopy. Four critical temperature points and liquid flow velocity at high temperatures of iron ores were obtained and the temperature points contain temperature at which sample starts to shrink, temperature at which the initial liquid phase forms, temperature at which a lot of liquid forms and temperature at which liquid consolidation ends. Under the same CaO to Fe203 ratio, the liquid phase fluidity of iron ore fines of Carajas （IOC） is good. However, under the same basicity, as the content of SiO2 in IOC is low, the liquid phase fluidity of IOC is much smaller than that of Yandi fine. After analysis of the initial formation and development of the liquid phase and the final consolidation process, the high-temperature process evaluation system （HTPES for short） of iron ore was established. The idea of ＂dense ore matching fusible ore＂ instead of ＂relatively fusible ore＂ was proposed based on the results of HTPES and applied in ore matching of a sinter plant from Shougang Jingtang. The use of IOC （13-18%） instead of standard sintering fines （SSF） improved liquid phase fluidity and ensured the sinter quality. Furthermore, the use of IOC fine （18-23%） with Hainan fine （0-2%） instead of SSF, a mixture of hematite and Marra Mamba ore and concentrates guaranteed the quality of sinter ore through improving fluidity, in the meantime reducing ore matching costs. With the establishment and application of HTPES, the sinter plant has achieved good economic benefits under the premise of ensuring the quality of sinter ore.
