Defect Control And Key Technology Research Of Low Temperature And High Toughness Ductile Iron Castings Produced In Electric Furnace Smelting

With the rapid development of wind power industry, wind power market demand for more and more high and low temperature toughness ductile iron castings, a 2MW wind turbine need hub, main frame, bearing, conical support, gear box of about 20 t ductile iron castings. Our country although in the development of high and low temperature toughness ductile iron made some achievements, but wind power Castings Technical requirements and quality requirements also continues to increase, most of the domestic casting enterprises are still unable to grasp the key technology, can not be a stable production out of qualified products.Report of inoculation, existed in the high and low temperature toughness ductile iron castings of wind power of a conical support as the research object, according to the company the actual production comprehensive mechanical performance is not stable, attached to the cast specimen spheroidization rate is low, the graphite is not round, thick at the ends of shrinkage hole, shrinkage porosity, porosity, surface slag from molten iron chemical composition control, raw and auxiliary materials, smelting furnace, the ball and casting process, the electric furnace smelting production of wind power at low temperature and high toughness ductile iron castings of key technology, and the box product material test using spark direct reading spectrometer and ICP analysis and other means of box single cast specimens and body cast test block of chemical composition Analysis using optical metallography metallography detection instrument on the morphology of graphite, graphite ball size were observed, control map spheroidization rate, ferrite and pearlite content analysis, using microcomputer control electronic universal testing machine to test the mechanical properties of tensile strength and elongation of the, using low temperature automatic impact testing machine for impact specimen of the low-temperature impact energy tested results for the guidance of wind cone supporting the actual production provides the basis.Wind to box product test results based, adjust the ball of breeding scheme, the mixed rare earth magnesium silicon alloy spheroidizing agent instead of yttrium based heavy rare earth spheroidizing agent, enhance the anti distortion of graphite, the long-term mixed inoculant packet inoculation to prevent the degeneration of inoculation, the sulfur oxygen pregnancy education agent with stream inoculation, adding the graphite nucleation core; at the same time, using Huazhu CAE casting filling and solidification process numerical simulation software, the simulation analysis of the casting temperature field and solidification state and to optimize the casting gating system. Based on the spheroidizing inoculation and pouring system adjustment and optimization, in a step by electric furnace smelting production and small batch conical support. The results revealed a tapered support The chemical composition, metallographic structure and mechanical properties of the cast samples are all meet the requirements of the cone support.