How to get the best inherent quality of castings
Cast Iron Smelting strict control of process parameters is to ensure that the key to inner quality casting.
(B) ductile iron production process parameters required
Ductile iron production, which seeks to be a small, round the whole, the uniform spherical graphite. Specific requirements are as follows:
1. Molten iron melting temperature:
a. To get a small, round the whole, the uniform spherical graphite morphology, we must first be dissolved into the eutectic crystallization of graphite critical radius below the melting temperature is higher than 1500 ¡æ.
b. To get a good elongation and strength properties must be made on the grain boundary oxide inclusions, melting a minimum of porosity. According to the former referred to the appropriate melting temperature should be above 1500 ¡æ.
c. Control the sulfur content of 0.03 ~ 0.02%, control the amount of coke to join, control the amount of carbon dioxide above the oxidation zone in order to reduce the sulfur into the amount of coke, its melting temperature should be higher than 1500 ¡æ, the temperature the higher the better control effect, in 1530 ¡æ best.
If we adopt the high-tech hot-air water-cooled cupola, has a high melting temperature: low-oxidative gas oxygen, non-lining operation, while slag basicity control to 1.7 ~ 2.3, can be furnace desulfurization, sulfur content down to 0.04 so that % of at this time, just a simple increase in the blast furnace or a continuous desulfurization equipment package desulfurization method can be used to control the sulfur content of a stable 0.02 ~ 0.038% in the best value within the agent can save the ball, stability, ductile iron production of high-quality ductile iron.
End on the above, ductile iron melting temperature of molten iron should be higher than 1500 ¡æ, stabilized at around 1530 ¡æ the best, no more than 1550 ¡æ.
2. Spheroidization treatment temperature
A suitable treatment temperature of the ball, the ball shall be guaranteed the full role of the agent, the proportion of lighter than iron oxides, inclusions and gas can be fully on the scum, its processing temperature suitable for international and domestic are in 1400 ¡æ, over golf agent loss is too large, too low, is not conducive to oxide slag and gas go up.
3. Inoculant by adding the temperature, the general context of the specific casting pouring temperature determined. However, we must control the inoculant with the size and pouring temperature. Instantaneous birth to a better way.
End on the above, ductile cast iron bridge of hot metal temperature should be controlled at or above 1500 ¡æ to 1530 ¡æ the best around.
