消除ZG15Mn磨辊铸钢件缩松缺陷的措施

ZG15Mn磨辊铸钢件属于低碳低合金钢厚大铸件,易产生夹杂、心部缩松、晶粒粗大等缺陷.第一次工艺方案是在铸件上方设2个圆柱形明冒口,结果在两冒口之间存在缩松；第二次工艺方案是在铸件上方设3个圆柱形明冒口,结果在3个冒口之间存在严重缩松.通过对缺陷原因进行分析,认为缩松是由于冒口的热作用很大,冒口与缩松区温度差较小,在最后凝固时,缩松区得不到冒口的有效补缩,造成了缩松.改进后的工艺方案是在铸件正上方设置一个圆柱形明冒口,冒口下设置补贴,形成顺序凝固,冒口向四周均匀补缩,使得铸件外圆的末端区作用发挥出来,从而使中间缩松区消失.经生产验证,新工艺不仅解决了缩松问题,而且铸件质量稳定.

Measures to Eliminate Dispersed Shrinkage Defect of ZG15Mn Roller Casting

ZG15Mn roller is a kind of low carbon and low alloy steel casting with heavy section,and defects such as inclusion,dispersed shrinkage and coarse grain occur easily.For both of the original casting processes with two and three cylindrical open risers,respectively on the top of the casting,dispersed shrinkage was found between the risers.This may be due to the small temperature difference between the riser and dispersed shrinkage area,so that at the end of solidification stage,the risers cannot feed the dispersed shrinkage area effectively.In the improved casting process,only one cylindrical open riser was set on the top of the casting and a patch was added under the riser,thus the sequential solidification was realized.The riser fed the casting evenly so that the dispersed shrinkage area disappeared.The practical production shows that with the improved casting process not only the shrinkage was eliminated,but also the casting quality was stable.