Pneumatic valve material quality inspection

for important pneumatic valve parts besides appearance surface quality inspection, and need for quality inspection within the material. Material of internal defects mainly include: non-metallic inclusions, interlayer porosity, crack, flake, delamination, uneven, composition segregation and coarse grains, etc. When materials within the above defects, will influence the strength of the mechanical properties and structure of the pneumatic valve, pneumatic valve life expectancy, serious accident happens, should be paid attention to for this kind of internal defects inspection and found that and stop this kind of material used as important on the pneumatic valve parts. Non-metallic inclusions,

the main secondary defects in casting or casting ingot as blank forgings, which has two kinds of sand inclusion and clamp design. Sand inclusion is in smelting casting, refractory lining of the debris fall into molten LianYe form. Clamp design is due to the melting LianYe during solidification molten slag not entirely the result of precipitation. These two kinds of defects in the material form of block, strip, flake inclusions or delamination defects. Interlaminar crack
are usually produced by high sulfur, phosphorus and hot crack. In the hot working process, because of burnt, osteoporosis, temperature control is lax or produced by the deformation. Displayed on the metallographic along the grain boundary or wear characteristic of grain boundaries. Pressure of pneumatic valve parts, therefore, in addition to the pump pressure test, must also choose important components for X-ray detector or magnetic particle inspection check. Porosity mainly exist in the casting internal material, due to the melting liquid to with Hugh, among them, some of which is formed by the chemical reaction gas release and local accumulation in some parts did not escape, porosity in a single second state is empty globose or elliptic, sometimes interpenetration, become curved insect ant porosity. Inspection methods namely ask nor crack inspection method.
。 White point check material section, sometimes is a silvery white spots, the rain is hydrogen in material decreases the plasticity and toughness of steel, hydrogen embrittlement accidents will happen in the use, should be according to the crack of macro or low power magnifying glass observation, metallographic inspection when necessary. Uneven coarse grains and grain
steel for lack of heat in the process of rolling, forging and make the ingot bulky items in the original grain of sichuan still remain. Also because of the ratio of rolling or forging than a hour, will form the uneven grain will affect the mechanical properties of materials. Main materials section observation and metallographic examination, to judge the defect.