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可锻铸铁生产对化学成分有严格的要求,例如:我厂的经验要求碳在2．3~2．6%;硅在1．3~1．5%(加铋时可提高到1．7~2．0%);碳硅总量应不大于3．9%;锰应为硫的2．4~3．2倍。碳低时易引起铸件裂纹,碳高时易产生疏松和麻口;硅低要延长退火周期,硅高亦易引起疏松和麻口;锰硫比过低或过高都会影响退火的结果。因此化学成分不稳定时,同一炉退火的可锻铸铁件有黑心、花心和白心等现象,铸件也有的好,有的是裂纹和疏松,质量没有保证。所以稳定可锻铸铁的化学成分是提高产品质量的首要关键。
The production of malleable cast iron has strict requirements on the chemical composition. For example, the experience of our factory requires that carbon should be 2.3-2.6%, silicon should be 1.3-1.5% (bismuth may be added to 1.7-2 .0%); total amount of silicon carbide should not exceed 3.9%; manganese should be 2.4 to 3.2 times the sulfur. Low carbon can easily lead to casting cracks, high carbon easily lead to loose and Ma mouth; low silicon to extend the annealing cycle, silicon can easily lead to loose and Ma mouth; manganese sulfur ratio is too low or too high will affect the results of annealing. Therefore, the chemical composition is not stable, the same furnace annealing malleable iron with black heart, flower heart and white heart and other phenomena, the casting is also good, some cracks and loose, there is no guarantee of quality. Therefore, the chemical composition of stable malleable iron is the primary key to improving product quality.