炸药熔铸过程缩孔和缩松的形成与预测

Formation and Prediction of Shrinkage Hole and Shrinkage Porosity in Explosive During Casting Process

采用工业CT对熔铸成型TNT及RHT(熔黑梯)药柱内部的缩孔和缩松情况进行检测,分析了炸药熔铸成型过程中内部缩孔缩松产生的模式和机理。采用有限元法对炸药熔铸成型过程中缩孔缩松的形成过程进行了数值模拟。结果表明,熔铸炸药内部缩孔缩松的形成主要是由于其凝固过程中结晶收缩、固体收缩及气体析出形成的,采用临界固相率和补缩距离相结合的方法可以有效预测熔铸炸药内部缩孔缩松的形成,在炸药熔铸成型时采用冒口保温、冒口和模具隔热及加大冒口尺寸等措施可以显著减少熔铸炸药内部的缩孔和缩松。

The shrinkage hole and shrinkage porosity and shrinkage distribution of casted TNT and RHT explosive charges were tested by X-ray computed tomography method.The shrinkage hole and shrinkage porosity formation model and mechanism were analyzed.The shrinkage hole and shrinkage porosity formation process at different conditions were simulated by using finite element method.The results show that the shrinkage hole and shrinkage porosity is mainly produced by crystal phase change,solid shrinkage and gas release during the solidification.Considering feeding length,the critical solid phase method can be used to predict the shrinkage hole and shrinkage porosity distribution in casted explosive charge.On the other hand,heat insulation between riser and mould,heat preservation on the riser and dimension increase to the riser can evidently decrease the shrinkage hole and shrinkage porosity during the casting process.