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The expert points out, China's foundry industry compared with the developed countries, mainly in the aspects of comprehensive quality of castings, casting production technology and technical equipment and other basic conditions. On the dimension precision, our castings generally lower than in developed countries 1 ~ 3, the surface roughness in developed countries than the diameter of 1 ~ 2. If the engine cylinder roughness, China is 25 microns to 100 microns, abroad for 12.5 and 25 micrometers. In the aspects of the castings, ductile iron cast products accounted for the proportion is an important index to measure the quality of a country's comprehensive structure of casting. Ductile cast iron and cast iron output ratio, there is a certain gap between the United States of America in 1996 as ductile iron accounted for 39.1% of the total output of cast iron with developed countries, China is 16.4%. In 2001, the United States 43.3%, China 22.45%. In recent years, although gap is narrowing, but of nodular cast iron and cast iron output ratio, there is still a large gap with the developed countries represented by the United states. Casting chemical composition, metallographic and performance level, the stability is generally lower than that of developed countries. In casting appearance, there is a large gap between China and developed countries.Developed countries generally advanced casting technology, products of good quality, high production efficiency, less environmental pollution, raw and auxiliary materials, has formed a series of commodity supply, such as in Europe, has established multinational service system. The production of the universal realization of mechanization, automation, intelligent (computer control, robotic operation). Cast iron smelting using large, efficient, dust, microcomputer control, external heat blast furnace lining of continuous operation without water cooling cupola, the widespread use of foundry coke, cupola furnace or electric furnace and the cupola furnace duplex melting process, shaking ladle desulfurization and sulfur content of the liquid iron up to below 0.01% by using nitrogen or continuous desulfurization; use of AOD, VOD and other equipment refining smelting alloy steel, the steel liquid in H, O, N reach several or dozens of 10-6 level. In the important castings in production, high requirements for materials, such as cast ductile iron P is greater than or equal to 0.04%, S is greater than or equal to 0.02%, P, S cast steel demand is greater than or equal to 0.025%, the thermal analysis technology, timely and accurate control of C, the content of Si, with direct reading spectrometer 2~3 minute analysis of ten elements content and high precision, C, S analysis and the regulation of the super low carbon stainless steel C, S content can be accurately controlled by nondestructive testing technology, effective control of the casting quality of advanced. |
