【摘要】 本文从理论上分析了大型船用铜合金螺旋桨皮下气孔形成的机理,在实验室条件下进行了皮下气孔模拟试验。针对缺陷形成的原因,在生产条件下采取了相应的工艺措施,不仅消除了皮下气孔,而且还大大减少了加工余量,实现了少余量铸造工艺,显著地提高了大型船用螺旋桨的质量。更多还原

【Abstract】 In this paper mechanism of sub-surface blisters formation in large copperalloy marine propellers has been theoretically analysed and studied with modeltests made in laboratories.High strength manganese-aluminum brass（ZHAI 67-5-2-2）and manganese-aluminum bronze（ZQAI 12-8-3-2）contain elements,such as Al,Mn,Zn,etc.,which have greater vapour while pouring and form oxides andhydrogen（e.g.Me+H₂o→Meo+H₂）.The hydrogen,formed by the metal-moldinteraction,dissolves and concentrates in the molten alloy.This is the importantfactor in the formation of sab-surface blisters.Baked portland cement mold easilyabsorbs moisture from the atmosphere.The higher the air humidity,the faster themoisture pick-up of the mold.Therefore skin drying with heated air must beemployed before pouring,together with an electro-detector for detecting the retainedmoisture and venting passages used,so that sab-surface blisters can be effectivelyprevented,allowance for machining reduced and casting technology with littlallowance realized.更多还原