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本文是研究稀土镁球墨铸铁在干砂型中冷却后所得到的各种不同的铸态珠光体量与热处理临界温度的关系。用膨胀法测定了不同的铸态珠光体量与临界温度的关系曲线,简称P—T曲线。在生产中用正火金相法对P—T曲线进行了验证,测定获得正火后珠光体量大于80%时,铸态珠光体量与二阶段正火分级温度的关系。用珠光体量、渗碳体量的多少来控制6300型柴油机球铁曲轴低碳奥氏体化正火的质量,使大断面球铁曲轴获得较好的综合机械性能。实践证明,P—T曲线可作为球铁热处理工艺参数(加热温度)制定的依据。应用P—T曲线对稳定球铁低碳奥氏体化正火、部份奥氏体化正火、淬火以及等温淬火的质量,对节约燃料的消耗都有深远的意义。
This article is to study the relationship between the amount of different as-cast pearlite and the critical heat treatment temperature after the rare earth magnesium nodular cast iron is cooled in the dry sand mold. The relationship between the amount of as-cast pearlite and the critical temperature was determined by the dilatometry method, referred to as the P-T curve for short. In production, the P-T curve was verified by normalized metallographic method. The relationship between the amount of as-cast pearlite and the second-stage normalizing temperature was obtained when the amount of pearlite after normalizing was over 80%. The amount of pearlite, the amount of cementite to control 6300 diesel ductile iron crankshaft low-carbon austenitizing normalizing the quality of the large-section ductile iron crankshaft to achieve better overall mechanical properties. Practice has proved that, P-T curve can be used as ductile iron heat treatment process parameters (heating temperature) to develop the basis. The application of P-T curve has a far-reaching significance for stabilizing ductile iron low-carbon austenitizing normalizing, partial austenitizing normalizing, quenching and the quality of isothermal quenching to save fuel consumption.