Casting technology! Effect of pouring temperature on casting! 1, pouring temperature is too high will greatly improve the proportion of waste
Pouring temperature is too high will cause sand up, especially with a complex sand core gray cast iron pieces, when the pouring temperature ≥ 1420 ℃ when the waste increased, pouring temperature of 1460 ℃ when the waste up to 50%. In the production, the use of induction furnace melting can better control the temperature of molten iron.

2, pouring temperature is too low may be the formation of defects
(1) Manganese sulfide stomata This stomata is located in the gray cast iron under the skin and more in the above, often exposed after processing, stomatal diameter of about 2 ~ 6mm. Sometimes the pores contain a small amount of slag, metallographic studies show that this defect is MnS segregation and slag mixing, because the pouring temperature is low, while the iron liquid containing Mn and S high.This amount of S containing and the appropriate amount of Mn (0.5% ~ 0.65%), can significantly improve the purity of molten iron, which effectively prevent such defects.

(2) sand core gas caused by the pores and porous air holes often caused by poor sand core exhaust. Because the core when the sand core in the core box in the hardening, which often makes the sand core exhaust number is not enough. In order to form the exhaust hole, the core can be added after drilling hardening.

(3) Liquid slag processing gray cast iron under the skin will find a single hole, the hole diameter is generally 1 ~ 3mm. In some cases there are only 1 to 2 holes. Metallographic studies have shown that these pores appear with a small amount of liquid slag, but no segregation of S is found. Studies have shown that this defect is related to the pouring temperature, casting temperature is higher than 1380 ℃, the casting did not find such defects, so the casting temperature should be controlled at 1380-1420 ℃. It is worth mentioning that the design of the gating system is changed and the defect can not be eliminated. Therefore, such defects can be considered to be due to the low pouring temperature and the pouring of molten iron in a trace reduction atmosphere. The most common cause of pouring temperature is that before pouring, the molten iron is transported and stuck in the open ladle for long periods of time. With a ladle cover with a thermal insulation material, the heat loss can be significantly reduced.