问:最近我厂用湿型生产一批球铁件,废品率很高,主要是铸件中产生缩孔和缩松。为此,我们不断增大冒口尺寸,铸件工艺出品率极低,然而上述缺陷仍不能消除。能否就这方面给予指导? 答:欲得到致密的铸件,首先需要了解球铁铁水冷凝过程中体积的变化规律,否则即使冒口体积很大,铸件内部也难免出现缩孔缩松缺陷。问:热胀冷缩是多数金属遵循的普遍规律,难道球铁有与之不同的地方吗? 答,是的。传统的冒口技术是采用顺序凝固原则,即通过 Q: Recently I produced a batch of ductile iron pieces with wet type. The rejection rate is very high, mainly resulting in shrinkage and shrinkage in the castings. To this end, we continue to increase riser size, casting process yield is very low, but these shortcomings still can not be eliminated. A: To get a dense castings, first of all need to understand the rules of volume change of the ductile iron in the process of condensation, otherwise even if the riser is large, it is inevitable that there will be shrinkage defects in the castings. Q: thermal expansion and contraction is the most common law followed by most metals, is it different ductile iron do? A, yes. The traditional riser technology is the principle of sequential solidification, that is, through