The grain size grade is about 4-5 class, and that during the thickness the central is less half a class than the lateral.

薄板坯的晶粒度的大致范围在4～5级，其中在厚度方向上薄板坯中心部位晶粒度比侧部小半个等级。

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The strength and toughness of super fine grain steels are greatly increased because of its micrometer or sub micrometer grade grain size.

超细晶粒钢依靠生成微米级或亚微米级的铁素体，使钢的强度和韧性大大提高。

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To break down the eutectic carbide network of A-cast structure with grain size 4-5 grade, tensile strain of 60% is needed.

当铸志晶粒度力4 ~ 5级寸，破碎晶炭化物组织需要有60%以上的拉应变。

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