Papers by Keyword: Casting Speed

Abstract: In continuous casting, the cooling rate, casting speed, and molten metal temperature significantly affect the quality of cast steel billets. Appropriate casting parameters can minimize quality problems such as surface, subsurface and interior crack, rhomboidity, oscillation mark depth, and central porosity. This research determines the relationship between defects and three significant factors temperature, cooling rate, and casting speed. The work has been performed on the two-strand continuous casting machine to investigate the billet (BS-4449 steel grade) cross-section of 150 x 150 cm². The defects analysis through macro examination at different tundish temperatures (1510 °C to 1560 °C), varying cooling rates, and casting speeds (0.9 to 1.6 m/min). The present study provides detailed insight into the three parameters mentioned earlier, which directly affect the quality of cast steel billets.

Abstract: The aim of this work is to investigate the effect of different casting speed in DC casting process and solution heat treatment of in situ Al-13.9%Mg₂Si composite. The increasing of DC casting speed not only makes primary Mg₂Si distribute more uniform and restricts segregation of primary Mg₂Si particles, but also it reduces primary Mg₂Si particle size. The DC casting speed significantly alter the eutectic Mg₂Si phase from fibrous to fine dot-like and eutectic phase refines effectively. The results obtained from mechanical testing demonstrated that the increasing of DC casting speed intensifies both hardness and tensile strength values. Then, the billet were subjected to solutionizing at 500^oC for holding time of 4h followed by quenching. The results indicate that the morphology of both primary and eutectic Mg₂Si changes after heat treatment. Solutionizing leads to the dissolution of the Mg₂Si particles and changes morphology from sharp edges to round shape. After solution heat treatment, tensile strength and elongation increase to 238.8MPa and 13.5%.

Abstract: In order to improve the quality of the billets, the whole test proceedings by the comparison of the two casting conditions which one is over heat 20°C-30°C under casting speed 0.4m/min-0.6m/min and the other is over heat 10°C-15 °C under casting speed 1.3m/min-1.6m/min are checked during the produce process of GCr15 in some domestic steel-making plant. The results show that the average grade of general porosity decreases 1.0, the average grade of center porosity down 0.5, the average grade of center segregation fall 0.5 and the samples tested in hot upset forging perform better than before. According to the results, the latter is determined to be accepted.

Abstract: According to the requirement of 20CrMnTiH steel, the effects of casting peed, EMS current intensity and secondary cooling system on internal quality of billets are studied. The results show that, it is beneficial to internal quality control of 20CrMnTiH billets when the casting speed is in the range of 1.2~1.4m/min, and when the current intensity of EMS is 380A, the level of center porosity can be controlled in 1.0, the index of carbon segregation can be controlled in 1.08 and equiax crystal ratio reaches 34.9%. Furthermore, it is beneficial to internal quality improvement when weak secondary cooling system is adopted. With the application of the studies, the quality of billet macrostructure and hardenability can meet the requirement of 20CrMnTiH steel.

Abstract: It was analyzed by strain-induced precipitation model that Nb(C,N) precipitation in micro alloy steel slab was effected by strain rate during continuous casting process. The results are as follows: The changing of casting speed could effect the time for 5%precipitation of Nb(C,N), which was decreasing with increasing casting speed at certain temperature and strain rate. Slab strain and strain rate were too small in bending zone and leveling zone. The effect of slab strain rate on Nb(C,N) precipitation could be ignore when Nb(C,N) precipitation in continuous casting process was studied.

Abstract: On the basis of problems about quality of steel products that a certain special steel factory facing, a heat transfer model about continuous casting process was first established, then the influence of casting speed on solidification process and solidification structure of continuously cast bloom was comprehensively studied. It is shown that shell thickness leaving mold, crater length and the value of H(which is chosen as the measurement criterion of the number of the heterogeneous nucleation nucleus) are influenced most with increasing casting speed. Meantime, compared with proportional control method, solidification process of continuously cast bloom is in uniform variation with small fluctuation by target surface temperature method. What’s more, when centre solidification time is considered only, central zone macrosegregation may form more easily at last by proportional control method with increasing casting speed, but it is opposite by target surface temperature method; when the value of G/V1/2 and the value of H are considered only, the ratio of equiaxed grain will increase with increasing casting speed by proportional control method, but it is opposite by target surface temperature method.

Abstract: The behavior of carbon and sulfur segregations of 82B hard wire steel produced under different continuous casting conditions has been systematically studied by the combination of field trial and laboratory analysis. The results showed three factors such as superheat degree, casting speed and F-EMS which influenced the segregation of billet worked differently with the variations of inner positions of the billet and segregation elements. For the central segregations of carbon and sulfur, the dominant factor was casting speed. Under high casting speed, proper increase of secondary cooling intensity could effectively decrease carbon and sulfur segregations of billet, especially for the central position of billet. The hydraulic simulation of the tundish showed the optimal casting speed should be 1.8m/min.

Abstract: Starting from the analysis of stresses on narrow side shell, based the principle that the stresses of narrow side shell will be less than the hot strength of cast steel grade, the maximum rate of displacement in course of freely bulging under hydrostatic pressure is deduced in this paper. And the speed of width adjustment is set based on which. Meanwhile the strain on wide side shell in width adjustment process is calculated. According to critical strain hypothesis, after investigation a proper casting speed is set to make the strain of wide side shell less than the critical strain and so to ensure the shell thickness in exit of mold meeting with production requirements.

Abstract: 7075 aluminum alloy ingot with the diameter of 100 mm has been produced by horizontal direct chill casting in different casting speed. The effect of casting speed on the sump profile and the ingot surface quality was studied by sump profile observation. It was found that increasing the casting speed results in the deepening of the liquid pool, the adding of segregation knots and the reducing of cold shouts in the ingot surface. It is also found that the depth of the liquid pool is directly proportional to the casting speed and the squared radius of the ingot.

Abstract: In twin-roll strip casting process, the casting speed has a significant influence on the metal flow and temperature distribution in the molten pool, which will affect the stability of this process and the quality of the produced products. Based on a 3D coupled thermal-flow analysis, a combination of the experimental results for twin-roll strip casting of stainless steel, heat equilibrium calculation and simulation results was conducted, and the boundary conditions of the heat exchange between the rolls and molten pool has been treated effectively. The effect of the casting speed on the flow and temperature in the molten pool was given. Simulation result is in agreement with the measured value.