Ductile iron castings and gray iron castings difference
Author: Sharon Date: 2015-9-30 10:10:52
1,gray iron flat sheet of graphite is flat,the ball is spherical graphite iron's. Percussion nodular cast carbon steel,such as percussion sounds similar issue,that of a good cast iron ball. The gray iron percussion sounds,boring.
2,the rate of problems on the ball,so to speak,the same ductile iron products,the ball of the different rates,and that the quality is different,the price is also very different. General factory has the ball of the rate of 85% for qualified products. Ball rate is below 85% because the casting time,there is no good and caused the ball of molten iron temperature is low,manufactured products,mainly the bearing pressure.
3,from the fracture (not machined surface) can simply distinguish the appearance of ductile iron and gray iron,with the naked eye,gray iron relatively coarse grain fracture for white,crystal face with metallic luster. Fracture of ductile iron grains are small,black and gray,if globalization is good,almost no metallic luster,gloss white if there is,in general,the emergence of white tissue.
4,from the smelting method,the ball is in the smelting of iron in the gray iron inoculant and Canada agent with the ball so that the scattered groups of graphite into spherical floc to reduce the fragmentation of ferrite,increasing the intensity ,Referring to the performance to achieve.
5,while the gray iron manhole covers are not to add any auxiliary materials,pig iron smelting into molten iron directly,and then poured into the wells. But the manhole covers are to add the ball of the agent,and other rare earth metal alloy made โโof magnesium,so now on the market and the relevant departments require manhole covers. That is because the manhole covers in the carrying capacity is far more than the gray iron manhole covers.
6,ductile iron casting,high strength,toughness,and therefore covers ductile than gray cast iron covers the same type of light about 30%. Ductile iron grades with QT500-7,hot metal tapping temperature not lower than 1456 โ,when the ball by treatment with rare earth ferrosilicon magnesium alloy and use low sulfur coke,the ball of the level of three or more.