精密铸钢件表面脱碳的防止措施

Countermeasures of Preventing Decarborization from Surface of Precision Steel Parts

在浇注前和浇注后分别向精密铸造型壳内通入氮气或丙烷气,采用不填砂浇注方法获得铸件。观察铸件表层组织,并进行硬度测试,分析采用各种方法减轻脱碳现象的原因。结果表明,通入两种气体均可以起到减轻或防止精铸件表面脱碳的现象,其中丙烷气防脱碳的效果较好,通入的气体占据了整个型腔,赶走了空气,隔绝外界空气的侵入,避免脱碳反应的发生,从而有效地防止了精铸钢件表面脱碳现象的发生。

The precision steel castings were produced with nitrogen(N2)or propane gas(C3H8)filling the shell mold before and after pouring liquid steel in case of sand-free.The microstructure was observed and the micro-hardness of the castings was measured on a type HXD-1000 micro-hardometer.The reason resulting in the relief of surface decarborization in the precision steel castings has been approached with protection gas.The results show that although both the N2 and C3H8 can effectively relieve or prevent surface decarborization in precision steel castings,C3H8 exhibits better prevention-decarborization effects.Surface decarborization in precision steel castings can be effectively eliminated as a result of removing the air in the shell mold.