The main results obtained are summarized as follows. The iron oxide skins are composed of Fe_3O_4, Fe_2O_3 and FeO, which react with carbon and form CO gas in the weld bead.

• 结果表明，氧化铁皮主要由Fe_3O_4、Fe_2O_3和FeO组成，并参与反应生成CO气体；