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What Are The Elements That Affect The Quality Of The Castings In Sand Casting?
Aug 16, 2017

  What are the elements that affect the quality of the castings in sand casting?

  Many peers may know that in the pig iron foundry, the general use of sand casting process is more extensive, pig iron in addition to iron, but also contains silicon, carbon, manganese, sulfur and phosphorus and other elements, the performance of these elements on the casting A certain influence. Here to introduce some of the other elements of pig iron:

  1, silicon (Si): can promote the carbon contained in the pig iron, can be deoxidized, but also reduce the casting of the gas, can improve the flow of molten iron, reduce the amount of casting shrinkage, but silicon More, will make the pig iron harder and brittle.

  2, carbon (C): in the pig iron in two forms exist, sand casting one is free carbon (graphite), mainly in the cast pig iron, the other is the combination of carbon (iron carbide), mainly in the pig iron , Iron carbide hard and brittle, low plasticity, the content can be appropriate to improve the strength and hardness of pig iron, too much content, then the pig iron is difficult to cut processing, which is the reason for poor pig iron cutting performance. Graphite is very soft, low strength, there can increase the casting performance of pig iron.

  3, manganese (Mn): soluble in ferrite and cementite. In the blast furnace refining pig iron, the appropriate amount of manganese can improve the casting performance and cutting performance of pig iron, manganese in the blast furnace and harmful impurities can form sulfur sulfide into the slag.

  4, sulfur (S): in the pig iron is a harmful element, which promotes the combination of iron and carbon, so hard and brittle, sand casting and iron synthesis of low melting point of iron sulfide, pig iron to produce hot brittleness and reduce the flow of molten iron , See the high sulfur pig iron is not suitable for casting pieces. The maximum amount of sulfur in the cast pig iron shall not exceed 0.06% (except for wheel pig iron).

  5, phosphorus (P): are harmful elements, but phosphorus can increase the mobility of molten iron, which is because the sulfur to reduce the melting point of pig iron, so in some products are often higher phosphorus content. However, the presence of phosphorus and iron to increase the hard and brittle, excellent pig iron and phosphorus should be less, sometimes in order to increase the mobility of phosphorus up to 1.2%.

  Pig iron generally refers to the iron content of 2 to 4.3% of the iron alloy. Also called cast iron. Pig iron in addition to carbon, sand casting but also contains silicon, manganese and a small amount of sulfur, phosphorus, etc., it can be cast forging According to the existence of carbon in the form of iron, can be divided into steel pig iron, cast iron and ductile iron and several other. The carbon in the pig iron is mainly in the form of iron carbide, and its cross section is white, usually called white iron. This pig iron performance is hard and brittle, and is generally used as a raw material for steelmaking. The carbon in the cast pig iron exists in flake-like graphite form, and its fracture is gray, usually called gray iron.

  As the graphite is soft, with lubrication, and thus cast pig iron has a good cutting, wear and casting performance. But its anti-bit strength is not enough, it can not be used for rolling, can only be used to manufacture all kinds of castings, such as casting a variety of machine tool castings, iron and so on. Ductile iron in the form of spherical graphite, its mechanical properties far better than the gray iron and close to the steel, it has excellent casting, cutting and wear resistance, a certain degree of flexibility, sand casting widely used in the manufacture of crankshaft, Gears, pistons and other senior castings and a variety of mechanical parts. In addition, there are silicon, manganese, nickel or other elements of the special high pig iron, called alloy pig iron, such as ferrosilicon, ferromanganese, etc., commonly used as steel raw materials. Adding some alloy pig iron during steelmaking can improve steel performance.