1, the iron graphite is flat, flaky, ductile iron graphite is in the shape of a ball. Percussion graphite cast iron, such as the issue of carbon steel sound similar to the sound, that ductile iron. The percussion sounds very dull gray.
2, is the gray iron manhole cover does not add any auxiliary materials, pig iron smelting directly into molten iron, then poured into the manhole cover. But ductile cast iron manhole cover is adding nodulizing agent, rare earth magnesium and other metal alloy to a, so now on the market and the relevant departments requirements for ductile cast iron well
Cover。 That is because ductile iron covers, in the bearing capacity is much more than the iron manhole cover。
3, on the rate of the ball, it can be said that the same is the ductile iron products, the rate of different, that quality is different, there is a big difference between the price. General factory has reached 85% of the rate of qualified products. The rate of less than 85% is due to casting when there is no ball
And the temperature of the molten iron is low, and the production of the product can not meet the requirements.
4, ductile cast iron, high strength, good toughness, so ductile iron covers than the same type of cast iron manhole cover light 30%. Using QT500-7 nodular cast iron grade, molten iron baked temperature not lower than 1456 DEG C, equipped with rare earth ferrosilicon magnesium alloy and selection of sulfur low spheroidizing treatment in coke.
The level of the ball up to three or more.
5, from the appearance of the fracture can simply the difference between ductile iron and gray iron, observed with the naked eye, gray iron fracture of relatively coarse grain size, gray white, crystal face with metallic luster。 The grain fracture of ductile iron is very small, if the ball is gray black, good words almost no metallic luster, if there is white
The general situation is shiny, white iron structure.
6, from the smelting method, ductile iron is in the smelting in gray iron with inoculant and spheroidizing agent make the graphite by dispersion of flocculent turn into a ball, to reduce the split of the ferrite, the strength increases, the mentioned properties to achieve the。
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