Ductile cast iron production process control

Ductile cast iron production process control
There are many factors affecting the stability of as-cast ductile iron production, steady production of nodular cast iron, must grasp well in the production of the following: the stability of the chemical composition and temperature of molten irons, accurate amount of iron liquid, appropriate nodularization and inoculation methods, as well as reliable in front of the furnace control.
1 equipment selection
1.1 smelting equipment selection of smelting equipment to choose first is on the premise of meet the needs of the production, follow the principle of high efficiency, low consumption. The advantages of the induction furnace is: fast heating, higher thermal efficiency of the furnace, oxidation burning loss is lighter, less absorbing gas. Using intermediate frequency electric furnace smelting, therefore, can avoid to add sulfur, phosphorus, P in the molten iron is not more than 0.07%, S no greater than 0.05%.
1.2 determination of spheroidizing package in order to improve the absorption rate of nodularizer, increases balling effect, spheroidizing bag should than normal iron liquid bag. Spheroidizing package of height and diameter ratio of 2:1 is determined.
2 raw materials choice
2.1 choose ductile iron burden of nodularizer to join effect on condition that: high carbon, low silicon and inoculation amount. To stabilize the chemical composition and controlled effectively promote white elements and anti-spheroidizing elements, and guarantee the quality of melting molten iron, choose zhang gang Z14 cast iron, its chemical composition: C > 3.3%, 1.25% ~ 1.60% Si, P, or less 0.06% S 0.04% or less.
2.2 the choice of nodularizer: nodularizer selection should be according to the different of smelting equipment, namely the tapping temperature and purity of iron liquid (such as sulfur, oxidation degree, etc.). Our country is the most commonly used rare earth magnesium ferrosilicon nodularizer, adopt the spheroidizing agent processing, due to the high silicon content in the alloy, can significantly reduce the intensity of magnesium reaction when processing. At the same time can also be due to increased silicon some role. Electric furnace production, due to the relatively high temperature, the chemical agent with a ball of are shown in table 1.
Table 1 nodularizer FeSiMg8Re7 chemical composition
Item tapping temperature/℃ S % Nodularizer composition/%
Mg Re Si
Electric furnace 1420~1480 ≤0.04 7.0~9.0 6.0~8.0 ≤44.0