Study On Melting Process Of Electron Beam Cooling Bed With Large Size Pure Nickel Flat

Pure nickel plate/strip has good corrosion resistance, mechanical properties and machinability performance, which is widely used in chemical industry, electronics, oil and gas, food, pharmaceutical, power, ships and other fields. Currently the traditional production process of domestic pure nickel plate strip is to first use a vacuum induction melting or a combination of vacuum consumable arc melting method of electrolytic nickel plate smelting ingot, billet and forging into slabs and then rolled into hot rolled/cold rolled plate and strip. Compared with foreign advanced level, domestic technology is relatively backward in pure nickel plate and strip, and the level of equipment, product quality, part of the high-performance, high-precision products mainly rely on imports, but also by foreign constraints. In this paper, look forward to using in the titanium industry, widely used electron beam cooling bed advanced smelting technology and independent development of a single cooling bed furnace smelting technology directly rolled into a coil, can be rolled directly cast large-sized flat ingots of pure nickel, iron and steel utilization rolling advanced equipment and technology industries, were pure nickel strip single cooling bed furnace smelting with direct rolling into research and development by improving the quality and shorten the process of nickel ingots (without forging/blooming process), to achieve high-quality cost-efficient manufacture of pure nickel strip.Due to the large diameter pure nickel ingot quality of subsequent pure nickel strip rolling process, microstructure and mechanical properties of has important influence. Therefore the electron beam cold hearth melting technology for casting the large size N6 pure nickel ingot (6000mm* 1050mm* 210mm) of different melting process parameters (the power of the electron gun and ingot pulling velocity matching) of nickel ingot quality (surface defects, chemical composition, elements segregation) effect and mechanism, and influence on subsequent hot rolled pure nickel strip microstructure and mechanical properties, and obtained the following research results:Pure nickel ingot produced in the electron beam cold hearth melting process main surface defect of crack, blowhole, inclusion, cold septum, hanging fold and condensation, the defect formation and cold hearth melting zone, overflow and mold zone electron gun power and ingot pulling speed is closely related to, through the coordination of the regional power of the electron gun and the selection of appropriate pull spindle speed can significantly improve the surface quality of ingot.Pure nickel ingot in electron beam cold hearth melting process in each region of the electron gun power selection and ingot pulling speed with the improper, will lead to the nickel ingot uneven chemical composition, carbon and iron elements appear different degree of segregation, and affect the subsequent hot rolled pure nickel strip on the microstructure and stress properties (tensile strength and elongation) equilibrium. The segregation behavior of elements in the flat ingot is mainly related to the evaporation rate is not balanced due to the selection of the power of the electron gun in each region and the speed of the spindle.Experimental results show that when the cold hearth melting region, overflow area, crystallization region of electron gun power respectively 720 kW,150 kW,360 kW, ingot pulling speed is 5 mm/min, the electron beam cold hearth melting of large-sized nickel ingot surface defect, less raw material utilization rate is highest, and the chemical into the uniform, the segregation degree minimum, and follow-up of hot-rolled nickel with volumes are organized in fine and homogeneous microstructure, mechanical properties (tensile strength and elongation) balance best.The research results of high quality and large size of pure nickel ingot electron beam cold hearth melting process optimization and direct rolling into tape technology development has important guiding significance and reference value, the jumbo wide high quality heavy pure nickel strip of high efficiency and low cost manufacturing has laid a solid foundation for the technology.