灰铸铁应用与发展的一些动向(2)

General Application and Development Trends of Gray Cast Irons(Ⅱ)

灰铸铁由于具有多种优越的性能,是目前用量最大的铸造合金。以汽车行业为例,从2010年开始,灰铸铁缸体、缸盖的用量逐渐增长。采用预处理工艺可以改善石墨结晶析出的生核条件,使铸铁的共晶转变温度提高,减轻过冷度,增加共晶团数量,减小铸铁力学性能参数值的波动范围,改善铸件的加工性能。灰铸铁中初生奥氏体枝晶是影响力学性能的重要因素,控制初生奥氏体增强灰铸铁的作用不亚于片状石墨的形态。详细叙述了S和Mn在灰铸铁中的作用及其发展,最后介绍了高Mn铸铁的研究和应用发展情况。

The gray cast irons had many excellent properties and therefore,they were the cast alloys used in the most large amount at present. Taking the automobile industry as the example, the usage amount of gray iron cylinder blocks and heads gradually increased since 2010. It was possible by using pretreatment to improve the nucleation condition of the graphite crystallization and separation, elevate the eutectic transformation temperature,reduce super-cooling degree, increase eutectic cell number,reduce the fluctuation range of mechanical properties parameters and improve machining properties of the castings. The primary austenite dendrite in the gray cast irons was the important factor influencing mechanical properties, and therefore, the effect of controlling primary anstenite to strengthen the gray irons was not inferior to the graphite morphology of the flake graphite. The effects of S and Mn in gray cast irons and development were described in detail. Finally the research and application development situation of the high Mn cast iron was introduced.