Nodulizer is a spherical additive in graphite crystallization in cast iron. The main elements of “spheroidized agent” are spherical elements, such as Mg, Ce, Ca, etc. The ductile graphite in ductile iron is spheroidized cast iron, so its strength is higher than that of gray cast iron, and its toughness is better than malleable iron, while cast iron. There are also a series of advantages to cast iron. However, when ductile iron is used to make molten steel helmets, ductile silver will increase the tendency of welding, white lips and tissue hardening, which will induce cracking in the welding and heat-affected zone (especially the fusion zone). Therefore, the weldability of ductile iron is worse than that of gray cast iron.
The commonly used nodulizer in China is ferrosilicon rare earth magnesium alloy. Most countries use magnesium nodulizers (pure magnesium and magnesium alloys), and some countries use calcium nodulizers.
The development of nodularizing agent plays an important role in promoting the production of ductile iron. Cerium was identified as a spheroidizer very early when the scarcity of cerium sources and the harsh conditions of the iron composition made cerium ductile iron unusable for industrial production. The magnesium atomizer before ductile iron has been applied in industrial production, and the development of nodularizers from pure magnesium to magnesium-nickel, magnesium-copper, and magnesium-silicon-iron alloys has promoted the expansion of ductile iron production. The development of rare earth magnesium ferrosilicon spheroidized silver iron ductile iron production in China is based on domestic resources, and the rare earth magnesium ductile iron series is established in my country to expand the use of live pigs. Do, improve the performance and quality of cast ductile iron, so that the production and development of ductile iron is more vigorous. The application of yttrium heavy rare earth creates conditions for the development of new composite nodulizers. The full utilization of various spheroidizing elements will create favorable conditions for the further development and improvement of ductile iron production.
The basic requirements of the nodulizer are:
(1) High spheroidization ability.
(2) Rich in resources, low cost and easy to dissolve.
(3) The ability to adapt to various components of iron (such as eutectic degree, sulfur content, containing anti-spherical elements and alloying elements) and temperature.
(4) The kinetic conditions of the spheroidization reaction are good, the reaction is relatively smooth, the reaction product is easy to remove, the dosage is small, the cooling is less, and the spheroidization treatment process is good.