Research On Development And Technology Basis Of Large Volume Roll

Pure nickel N6 has good resistance to high-temperature creep performance, good corrosion resistance, mechanical processing performance, and has some special physical, therefore N6 has been widely applied in semiconductor integrated circuit, microelectronics industry and aerospace industry, and many other areas. N6 is an indispensable material in modern industries. At present, the smelting of domestic pure nickel is mainly prepared by non-vacuum induction melting, inspiratory problems in smelting process and control problem of alloy elements are still can not be solved. In recent years, the use of electrolytic nickel, since the power vacuum arc furnace for melting, this method can solve the problem of electrolytic nickel material loose better, and improve the state of internal gas impurities such as deficiencies, but the practice shows that there is no guarantee that eliminate inclusions and segregation can be solved, thus it hard to get satisfactory ingot casting. And ingot after remelting process, make process becomes more complex, production cycle becomes too long, thus the yield becoms low, cause high cost of processing, greatly reduces the market competitiveness of nickel plate, wire rod. And the breadth of the domestic haven’t mature nickel roll rolling technology and professional equipment, so that the production of nickel plate, with the weight of the basic under 500 kg, are unable to meet the automated assembly line production of nickel belt and processing enterprises of production requirements, directly affect the nickel plate, with the development of processing industry.In this paper, select the large electron beam cooling bed of melting furnace in yunnan titanium industry Co., Ltd to smelt large size pure nickel ingot, the nickel smelting with large flat ingot belongs to the technical innovation. The difficulty of smelting lies in how to coordinate the process parameters, stable melting process, control smelting macroscopic defects and element segregation, thus lays the foundation for subsequent hot rolled Ni volume. Gleeble-3500 was employed to do hot simulation experiment in this study, the material cut into cylinder(deformation temperature is 950-1100℃, the strain rate of 0.001-10 s-1, the dependent variable is 60%) combined with hot compress test data N6 under different deformation parameters of hot working diagram, under the condition of different deformation by means of optical metallographic microscope system research and analysis on the microstructure evolution regularity, to provide reasonable hot rolling process parameters for industrial production. Finally, cold-rolled nickel N6 plate after the heat treatment process, eliminate the cold rolling process of the mechanical properties of impact the work hardening, to the national standard requirements. The main research results are as follows:(1) Electron beam cooling bed furnace was used to smelting pure Ni flat ingot, uneven surface temperature of melt and local overheating is a major cause of lead to segregation nickel ingot. The electron gun power in melting zone, overflow zone and the crystalline region more evenly, the melt surface mean temperature difference is smaller, C, S and Fe content in nickel ingot is lower and the degree of segregation became smaller. Appropriate decreasing spindle speed can make the electron gun on the melt surface scanning prolonged, scanning more fully, make the melt surface temperature more uniform, thereby reducing the degree of segregation. Adding suitable amount of Mn, Al, Ti element into smelting, can improve the degassing in the process of smelting process, at the same time, also can improve the strength of materials. In this experiment, when adding 0.02% Ti,0.01% Mn,0.015% of Al, melting zone, overflow zone and crystalline region electron gun as 6A current, when the spindle speed of 5 mm/min for the nickel ingot quality best.(2) By studying the hot compression rheological behavior of Ni, and draw hot working diagram of Ni, it was show that the dependent variable of N6 has a little influence on the choice of reasonable processing area, in low temperature and low strain rate (deformation temperature 950 ℃, strain rate 0.02S-1-0.3S-1), high temperature and low strain rate(deformation temperature 1100℃, strain rate 0.001 S-1-0.006S-1) is the best processing area. But due to the high temperature is not conducive to the generation of dynamic recrystallization, so the best processing parameters of N6 is high temperature and low strain rate(deformation temperature 1100 ℃, strain rate 0.001 S-1-0.006S-1).It can provide reasonable hot rolling process parameters for industrial production.(3) By different annealing temperature experiment, it is concluded that with the increase of annealing temperature, the hardness of Ni had a downward trend, while before 500 ℃, the tensile strength and yield strength decreased and then had a higher volatility trends, after 500℃, the tensile strength and yield strength continues to fall. Because of the beginning of recrystallization process and precipitated phase around the boundary, makes the tensile strength and yield strength changed. Elongation presents the downward trend and then declined, maximum elongation exist at 500℃ due to lots of uniform distribution of recrystallization particles exist. After cold rolling, annealing at 500℃for 1 h, eliminate the work hardening phenomenon, the comprehensive mechanics performance of materials to achieve the best.