2014.06.08 Shanghai kai rich industrial co., LTD. (www.xfmjgy.cn) sales of P20 steel dies information: with the development of auto industry and the competition between industry, comprehensive mechanical properties and performance of automotive castings of the demand is higher and higher, so the high grade of as-cast nodular cast iron production application research, to improve product quality and competitiveness is of positive significance. This research embarks from the actual production, by controlling the casting of the chemical composition, improved breeds, especially the adjustment of alloying addition amount of Mn element, get the as-cast pearlite - existing body of the mixing matrix high grade of nodular cast iron, while reduce casting production cost, improve castings quality, and at the scene of the transit single tyre wheel production project. L in nodular cast iron manganese can hold up the decomposition of cementite and ferrite, because in the ductile iron manganese rarely combined with sulfur, and the main stabilizing effect of pearlite and carbide, can make the as-cast pearlite increases and refinement. Manganese can be solid soluble in ferrite, strengthening the role of the ferrite. Rich 2014.06.08 Shanghai kai industrial co., LTD. (sales P20 steel www.xfmjgy.cn) information: as a result, in the as-cast high grade of nodular cast iron pieces in production practice, the content of manganese is very important, general process control in the 0.4% to 0.6%, and is generally accepted that high manganese content in the ductile iron segregation is serious, can reduce the impact toughness of the casting. This research breakthrough tradition in the production of ductile iron on the limitations of manganese addition amount, the increase the content of manganese, obtain comprehensive mechanical properties conform to the requirements of as-cast high grade of nodular cast iron. 2.1 2 test results and analysis of test results for the amount of manganese changes the mechanical properties of ductile iron were investigated and the influence of the microstructure as shown in table l. Sample from table l Cll, C12, D11, manganese content increased from 0.48% to 1.2%, the strength from 473 mpa to 738 mpa, the hardness increased from HBl70 to I -- IB240, while elongation decreased from 21.86% to 21.86%. So in improving carbon, guarantee the spheroidizing, under the condition of more breeds, manganese content in o. 7 - o. 9% range to produce QT500-10, QT550-7, the manganese content in the 0.9-1.1% range to produce QT600.5, QT700.3. Table lMn addition amount of changes on the influence of mechanical properties. 2014.06.08上海偕富实业有限公司（销售P20模具钢www.xfmjgy.cn）的资讯：因此，在铸态高牌号球墨铸铁件的生产实践中，对锰的加入量控制显得十分重要，一般工艺上控制在０．４％－０．６％，并普遍认为过高的锰含量在球铁中偏析严重，会降低铸件的冲击韧性。本研究突破传统球铁生产中对锰加入量的局限，采用提高锰加入量，获得综合机械性能符合要求的铸态高牌号球墨铸铁。２试验结果与分析２．１试验结果锰加入量的变化对球铁试样力学性能和金相组织的影响如表ｌ所示。