Engine cylinder liner referred to as the cylinder liner, the material of the cylinder liner is generally ductile cast iron and alloy cast iron, which requires hardness of HB200 or more, tensile strength is not less than 200MP, so that there will be good wear resistance, corrosion resistance, high temperature resistance. The main reason is that because the cylinder has been in a high temperature and high pressure working environment, and the high-speed piston phase friction is easy to appear wear phenomenon, if it is a wet cylinder liner, the appearance is directly in contact with cold water shortage, strong temperature difference will produce serious thermal stress, will be corroded by cooling water. Therefore, if the material used does not meet the requirements, it will increase the maintenance cost and affect the engine performance.
What is ductile iron? Ball mill cast iron is iron containing a certain composition of spherical carbon. Its main characteristics are as follows: 1, impact resistance and ductility is very good, the carbon element of graphite will enter the iron element, greatly strengthen its impact resistance, although the graphite is not malleable but the ductility of iron is very strong, the perfect combination of the two makes ductile iron have impact resistance and ductility. 2, to prevent cracking, the graphite ball has a very high stability, the probability of cracking is very small, some studies have found that the iron in the cracking to the place where there is graphite stopped; 3, corrosion resistance, because there are carbon elements in iron, so that corrosive substances greatly reduce the corrosion of iron;
Alloy cast iron is to add alloying elements to iron, such as silicon, manganese, phosphorus, nickel, chromium, molybdenum, copper, aluminum, boron, vanadium, titanium, antimony, tin, etc.; Alloy cast iron is divided into low alloy cast iron, medium alloy cast iron and high alloy cast iron according to the amount of alloying elements added. The addition of alloying elements can make the basic structure of pig iron change, so that the cast iron has more powerful corrosion resistance, high temperature resistance, wear resistance, such as phosphating cylinder liner (below).
The specific engine cylinder liner should choose what kind of material, depends on the working environment and conditions of the engine, alloy cast iron cylinder liner is generally suitable for high temperature, high pressure, overload, conditions are very bad large engine units or construction machinery; If it is a general machine tool or car engine can choose the ball mill cast iron cylinder liner, not only can meet the daily operation and the price is relatively low.