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将某些球铁于铝浴中循环快速加热和冷却以使其基体组织微细化,并在其共析转变温度区间附近进行拉伸试验,便可确定球铁中有无超塑性现象发生。在M_(10)(含M_n量为1.0％)的F+A+F_(e3)C温度区间及M15(含M_n量为1.5％)的A+F_(e3)C温度区间,流变应力的高的应变速度敏感性指数,表明有超塑性。M_(10)与M_(15)的应变速度敏感性指数不是常数,在高的应变速度时它逐渐减至与M_(o3)(含M_n量为0.3％)相近的数值。加M_n合金化扩大了形成微细组织的温度区间,因而允许高的试验温度。由于在石墨两侧空洞的形成导致早期断裂,因而就得不到象有色金属超塑性材料那样高的延伸特性。微细组织球铁与通常的球铁相比具有高的室温强度和塑性。
Some of the ductile iron in the aluminum bath cycle rapid heating and cooling to make the matrix microstructure, and in the vicinity of its eutectoid transformation temperature range of tensile test, you can determine whether there is superplasticity in the ductile iron. In the F + A + F_ (e3) C temperature range of M_ (10) (containing 1.0% M_n) and the A + F_ (e3) C temperature range of M15 High strain rate sensitivity index indicates superplasticity. The strain rate sensitivity index of M_ (10) and M_ (15) is not constant. At high strain rates, it gradually decreases to a value similar to that of M_ (o_3) with an M_n content of 0.3%. Adding M_n alloying expands the temperature range for the formation of microstructures, thus allowing for high test temperatures. Since the formation of voids on both sides of graphite leads to early rupture, elongation properties as high as non-ferrous metal superplastic materials are not obtained. The microstructure ductile iron has high room temperature strength and ductility compared to the usual ductile iron.