A roll mill is producing small and medium-sized centrifugal rolls. The water spheroidizing agent is made of rare earth magnesium ferrosilicon alloy (FeSiMg8RE5), and the rare earth magnesium ferrosilicon alloy is added in an amount of 1.80%~2.30%. A rare earth magnesium ferrosilicon alloy is used as a spheroidizing agent, and is spheroidized by a punching method. The inoculant is made of ferrosilicon (FeSi75), and the amount of inferred ferrosilicon is 0.5O% to 0.80%. The use of rare earth magnesium-silica alloy as a spheroidizing agent and the use of ferrosilicon as an inoculant have been used for more than ten years, and the spheroidization of small and medium-sized centrifugal rolls has been very good and stable. However, when developing medium-sized steel and roughing mill centrifugal rolls, it was found that the core of the centrifugal roll was spheroidized and the tensile strength of the roll was significantly reduced.
A roll mill is producing small and medium-sized centrifugal rolls. The water spheroidizing agent is made of rare earth magnesium ferrosilicon alloy (FeSiMg8RE5), and the rare earth magnesium ferrosilicon alloy is added in an amount of 1.80%~2.30%. A rare earth magnesium ferrosilicon alloy is used as a spheroidizing agent, and is spheroidized by a punching method. The inoculant is made of ferrosilicon (FeSi75), and the amount of inferred ferrosilicon is 0.5O% to 0.80%. The use of rare earth magnesium-silica alloy as a spheroidizing agent and the use of ferrosilicon as an inoculant have been used for more than ten years, and the spheroidization of small and medium-sized centrifugal rolls has been very good and stable. However, when developing medium-sized steel and roughing mill centrifugal rolls, it was found that the core of the centrifugal roll was spheroidized and the tensile strength of the roll was significantly reduced.
The engineers analyzed that the main reason for the poor spheroidization of the core of the medium-sized steel centrifugal roller and the coarse SLSL centrifugal roller is that the roller has a large diameter (500mm to 700mm) and the cored iron has a large amount of water (2.0 to 3.0t). After the pouring, the cooling time is longer. The original spheroidizing agent and the inoculant cause the spheroidization of the core, and the spheroidization of the core is more serious, and the strength of the core of the SL~$L roller is lowered. After switching to the ruthenium-based heavy rare earth D-1RP long-acting spheroidizer and the silicon germanium long-acting inoculant, the problem of spheroidal fading of the centrifugal core of the medium-sized steel centrifugal roll and the rough rolling mill was basically solved. The method of adding the bismuth-based heavy rare earth spheroidizing agent and the silicon germanium long-acting inoculant is the same as the original use of the rare earth magnesium iron alloy spheroidizing agent and the ferric inoculant.钇-based heavy rare earth long-acting spheroidizing agent D. The amount of 1RP added is 1.8% to 2.0%, and the main components are: heavy rare earth W (RE) is 2% to 3%, W (Mg) is 6.5% ± 0.2%, W ( Ca) is 1.8% to 2.0%; the long-acting inoculant of silicon germanium is added in a mass fraction of 0.8% to 1.2%, and the main component: W (Ba) is 4% to 6%, W ( Ca) 2.0%, W (Si) is 70% 71%, W (A1) < 1.2%. After using the bismuth-based heavy rare earth long-acting spheroidizing agent and the silicon germanium long-acting inoculant, the core spheroidization decay is greatly reduced, and the tensile strength of the rough rolling centrifugal roll neck is obviously improved. According to the data, the molten iron is at 1350 to 1400 °C. The decay rate of the mass fraction of magnesium is 0.001% to O. At 004%/min, the decay rate of the mass fraction of light rare earth lanthanum is 0.0006% to 0.002%/min, and the mass fraction decay rate of heavy rare earth lanthanum is 0.0008%/min. It can be seen that the rate of decay of the mass fraction of heavy rare earth is slower than the rate of decay of magnesium. The medium-sized centrifugal roll core-filled iron uses a long-acting ball-forming agent of cerium-based heavy rare earth and a long-acting inoculant of silicon germanium [2], which fundamentally solves the technical problem of the spheroidization of the core of the medium-sized centrifugal roll.
