汽车发动机曲轴的受力情况很复杂,它承受着扭矩、弯矩和冲击等负荷,因此,对曲轴的材料提出了较高的要求。另外,曲轴的铸造表面要求光洁、平整、不粘砂、不错箱,内部宏观组织不得有疏松、缩孔、气孔、裂纹、夹渣等缺陷存在。一、球铁的铸造工艺特点1.易产生氧化皮、夹渣和皮下气孔。球铁铁水中常存有硫化镁、氧化镁等,经球化处理后,还残留一定数量的镁或镁-稀土元素,使铁水的物理化学性质发生一定的变化,铁水 The stress on the crankshaft of the automobile engine is very complicated. It is under the loads of torque, bending moment and impact. Therefore, the crankshaft material has higher requirements. In addition, the crankshaft casting surface requires smooth, smooth, non-stick sand, good box, the internal macro-organization may not loose, shrinkage, porosity, cracks, slag and other defects exist. First, the ductile iron casting process characteristics 1. Easy to produce scale, slag and subcutaneous pores. Ductile iron hot metal often contain magnesium sulphate, magnesium oxide, etc., after the ball treatment, but also a certain amount of magnesium or magnesium - rare earth elements, so that the physical and chemical properties of molten iron have some changes, hot metal