As a manufacturing enterprise, enterprises must make great efforts in lean production in order to be competitive in the market economy.
At the end of the Warring States period, the nephew said: "There is no accumulation of steps, no more than a thousand miles; no accumulation of small streams, no rivers and seas." It can be seen that a good foundation is so important to you in society. There is such a writer, the room has a strange decoration, whether it is curtains, a shelf or kitchen utensils are hanging paper, each piece of paper is hung with wonderful words, he puts the paper in every corner of the room In order to remember every moment, it is precisely because of this perseverance of the language that he wrote the popular works such as "Love Life" and "Iron Horse". He is the famous American writer Jack London. .
High-quality products are the foundation of a company's development. It is precisely because of the excellence of the products that Anhui Jiuhua Fukang Foundry Materials Co., Ltd. has a good reputation. The spheroidizing agent stands out among many casting materials. So what is the problem? What happens when the spheroidizing agent is not used?
Graphite ball dissimilation
Graphite ball dissimilation occurs in irregular graphite, such as agglomerates, braids, worms, horns or other non-spherical shapes. This is due to the fact that the local crystal growth mode and growth rate deviate from the normal growth law when the spheroidal graphite grows in the radiation direction. When the amount of residual spheroidal elements in the casting exceeds the expected range, if the residual magnesium is too high, which exceeds the minimum amount required to maintain the spheroidization of the graphite, it will also affect the crystallization condition of the graphite, and it is easy to produce reinforced graphite. When there are many residual rare earths, high carbon equivalent iron water is easy to produce broken graphite, and the concentrated area of broken graphite is generally called "grey spot". The appearance of worm-like graphite is due to insufficient residual spheroidal elements or excessive titanium and aluminum.
Graphite floating
In the thick-walled ductile iron with hypereutectic composition, at the top of the casting position, a graphite-rich area often appears, that is, the phenomenon of “floating at the beginning and ending”. This is because the density of graphite and molten iron is different, and the graphite directly precipitated by the hypereutectic molten iron is buoyant. Caused by upwards. The degree of graphite floating is related to factors such as carbon equivalent, type and residual amount of spheroidizing elements, solidification time of castings, and pouring temperature. Magnesium can increase the eutectic carbon content of ductile iron. The molten iron with the same carbon equivalent can increase the residual magnesium content and reduce the floating of graphite. The residual rare earth content is too high, which is helpful for the rise of burst graphite.
Anti-white mouth
Generally, the white mouth structure of cast iron parts tends to appear in the surface layer, sharp corners, creases, etc. where the cooling is faster, and the reverse white mouth defects are opposite. The carbide phase appears in the middle part of the casting, the hot section and the like. When the residual amount of the spheroidal element is too large, there is an effect of promoting the occurrence of the anti-white mouth defect. The rare earth element is stronger than the magnesium, and they generally increase the degree of subcooling in the formation of ductile iron. The subcutaneous needle hole in the subcutaneous needle hole mainly contains hydrogen, and also has a small amount of carbon monoxide and nitrogen. When the amount of residual magnesium is too high, the tendency to absorb hydrogen from the wet type is also enhanced, and the probability of subcutaneous needle holes is increased. In addition, the long residence time of the spheroidized molten iron can also increase the number of pinholes. Shrinkage shrinkage shrinkage holes often appear in the final solidification part of the casting (hot joint, the neck of the riser neck and the joint of the casting, the inner corner or the joint between the inner gate and the casting), and are holes hidden in the interior of the casting or communicating with the exterior. Shrinking, macroscopic appearance in the hot section, fine shrinking holes, mostly inside the holes. Related to the spheroidal element is to control the residual magnesium and rare earth can not be too high, which has a significant effect on reducing macroscopic and microscopic shrinkage, and the tendency to shrink is almost proportional to the spheroidized element. Black slag generally occurs in the upper part of the casting (casting position) and is mainly divided into blocks, ropes and finely divided black slag. The main component of black slag, magnesium silicate, is formed by the reaction of MgO and SiO2 in molten iron and is affected by its relative content. Therefore, as one of the measures to control the black slag is to reduce the residual amount of magnesium (the total amount of slag is about 0.1% of the weight of the molten iron when 0.15% of magnesium is added), and the residual rare earth has a strong affinity with oxygen, and the black is reduced. The slag has obvious effects. Spheroidization decline is due to the longer residence time of spheroidized molten iron, the residual magnesium is gradually reduced, the slag is not removed in time, and the sulfur will return to the molten iron, so that the graphite in the solidified structure is reduced or even disappeared, and the decay becomes irregular. Worm-like or flake graphite. This spheroidization decline has a certain relationship with the low content of rare earth in the spheroidizing agent or the low amount of spheroidizing agent added, but it is also undesirable to increase the amount of spheroidizing agent, because the residual amount of magnesium is high, and the amount of slag is high. Both cementite and cementite will increase, and in the thick section, the graphite spheres will become stellite graphite. Production practice shows that the low sulfur content of the original molten iron is the most effective to prevent spheroidization decline. Including some ductile iron defects, almost all related to the composition and amount of spheroidizing agent, but we can not expect the spheroidizing agent to solve many problems, but can not solve all problems, because the role of spheroidizing elements and spheroidizing agent The amount of addition is a coexistence of advantages and disadvantages. The spheroidizing agent is only a very important factor in the stable production control system of ductile iron. Only when combined with other supporting measures, can it be stably spheroidized.
Anhui Jiuhua Fukang Foundry Materials Co., Ltd.
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Address: Muzhen Industrial Park, Qingyang County, Chizhou City, Anhui Province
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