介绍了壳体类球墨铸铁件出现表面锈斑缺陷的典型特征:(1)HWS线生产的减速器壳、平衡轴支架外表面及转向节内腔与外表面有锈斑;(2)消失模生产的减速器壳的外表面复杂部位及圆柱齿轮壳的内腔有锈斑;(3)DISA线生产的卡钳体内腔有锈斑.分析了表面锈斑缺陷产生的主要原因,认为在随流孕育时,孕育剂中的w(Ca)量过高,过多的Ca元素在铸件凝固过程中来不及被铁液吸收,Ca元素经过化学反应产生的CaO、CaS夹渣易吸潮导致铸件表面产生电化学腐蚀,使铸件表面产生锈斑.通过试验分析,并通过实践证明:采用随流孕育时,降低高效孕育剂中的w(Ca)量或采用75SiFe粉孕育剂,均可有效消除壳体类球墨铸铁件的表面锈斑缺陷.%Typical charateristics of housing-shaped nodular iron castings producing surface rusty spots were introduced:(1) The housing of velocity reducer,outer surface of balance shaft bracket and internal cavity of turning knuckle produced on HWS line had rusty spots.(2)Complicated places on the surface of the velocity reducer housing and internal cavity of cylindershaped gear wheel housing produced with EPC process had rusty spots.(3)Internal cavity of the calipers body produced on DISA line had rusty spots.The reasons of surface rusty spots formation were analyzed.It was considered that due to Ca content of the inoculant used for stream inoculation too higher,and the redundant element Ca could not be absorbed in time by the iron melt,then,by the chemical reaction,the element Ca produced CaO and CaS slags which was easy to absorb moisture and caused electrochemical erosion that caused rusty spots on the surface of castings.By test analysis and productive practice,it was proved:both reducing Ca content of the high effective inoculant used for stream inoculation,or using powder 75SiFe inoculants could eliminate rusty spots on the surface of housing-shaped nodular iron castings.
展开▼
