| BFe30-1-1 copper-nickel alloy has good corrosion resistance,which is usually used as a special tube for the manufacture of condensers and is widely used in petrochemical industry,naval ship manufacturing,seawater desalination and other fields.For the vertical continuous casting technology of large-diameter hollow ingot of BFe30-1-1 alloy,China has not yet developed and put into production,and it is prone to‘drawing leakage’,‘core cladding’,mold cracking,slab cracking and other issues in production.Continuous casting process is a key factor affecting the quality of slab.Aiming at the practical problems of a copper pipe factory in China,the hollow ingot vertical continuous casting process ofΦ260×Φ80 mm andΦ454×Φ260 mm was studied by using the finite element simulation software Pro CAST.In order to compare withΦ454×Φ260 mm hollow ingot,Φ454 mm solid ingot was also studied.The effects of casting temperature,casting speed,cooling intensity of primary cooling zone and cooling intensity of core tube on temperature field,stress field and slab microstructure during solidification were studied.The rationality of continuous casting process was judged based on the depth of liquid cavity and the maximum equivalent stress of mold.The tendency of crack defects in slab and mold during continuous casting was analyzed from a macro perspective,and the reasonable casting process parameters were determined,which provided theoretical reference and process guidance for the actual production of BFe30-1-1.In order to analyze the influence of casting process parameters on temperature field,the cavity morphology was studied.The liquid hole depth increases with the increase of casting temperature,decreases with the increase of primary cooling strength,decreases with the increase of core cooling strength,and increases with the increase of drawing speed.Based on orthogonal experiment and variance analysis,the influence of drawing speed on liquid hole depth is the most obvious.The evolution law of solidification structure during continuous casting was analyzed.The steady state model of continuous casting was established,and the solidification structure of three kinds of billets was simulated by cellular automata.The influence of continuous casting process parameters and nucleation parameters on the microstructure ofΦ454×Φ260 mm hollow ingot was analyzed.Based on orthogonal experiment and variance analysis,the reasonable continuous casting process parameters of different specifications of hollow ingot were obtained.For the hollow ingot withΦ260×Φ80 mm,the reasonable casting temperature was 1260°C,the blank drawing speed was 80 mm/min,the interfacial heat transfer coefficient of the primary and secondary cooling zones was 3000 W/m~2·K,and the core tube was cooled by air.ForΦ454×Φ260 mm hollow ingot,the reasonable casting temperature is 1280°C,the drawing speed is 55 mm/min,the interfacial heat transfer coefficient of the primary and secondary cooling zones is 3000 W/m~2·K,and the core tube is cooled by air.TheΦ454×Φ260 mm hollow ingot was verified by reasonable process parameters,and the hollow ingot product meeting the quality requirements was successfully trial-produced. |
