【摘要】 采用反重力铸造凝固,通过观察统计四种不同氢含量试棒中的孔洞,研究氢含量和冷却速度对铝硅合金铸件中孔洞形成的影响。研究发现,氢含量对孔洞缺陷的形成至关重要,相同凝固条件下,氢含量高的熔体更易形成孔洞;随熔体氢含量增高,孔的个数和孔隙率增大;只要氢含量足够低,即使凝固补缩状况很差,也难以形成大孔;冷却速度也影响孔洞形成,快的熔体冷却速度可有效减少孔洞个数和尺寸;在凝固过程中冷却速度和氢含量共同作用影响孔洞形貌、数量、尺寸及孔隙率。更多还原

【Abstract】 Four Al-Si alloy specimens with different hydrogen content were fabricated by counter-gravity casting,and the effects of hydrogen content and cooling rate on formation of porosity in the alloy were investigated.The research shows that hydrogen content plays a crucial role on porosity defect.At same solidification condition,melt with high hydrogen content is liable to form pores;as the hydrogen content became higher,the number of pores and volume fraction of pores increase.As long as the hydrogen content is low enough,it is hard to form big pores even if melt feeding is poor.Cooling rate also exerts an important influence on the formation of pores.Rapid cooling can effectively decrease the number and size of pores;in the process of solidification,hydrogen content and cooling rate corporately determine the number,size and volume fraction of pores.更多还原