There are hydrogen hole, nitrogen hole, the pore of carbon dioxide, the pore of carbon monoxide and oxygen hole etc. according to the gas composition classfication in pore.

• 气孔的形成机理常温固态金属中气体的溶解度只有高温液态金属中气体溶解度的几十分之一至几百分之一,熔池金属在凝固过程中,有大量的气体要从金属中逸出来。