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引言 熔模铸造工艺复杂,部分铸件精度要求高,加工后经常因皮下气孔,内部夹渣、砂眼等缺陷造成报废,其数量有时高达50％。气孔缺陷大部分在距离表面1.5毫米处,直径约为φ0.5～φ4毫米,也有小于φ0.5毫米的针孔。气孔呈圆型或椭圆形,较有规律地分布在铸件内浇口上部,少量分布在工件其它部位。 选用直流磁化探伤法能准确可靠地反映出铸件内部深度在5毫米左右,直径大于0.5毫米的皮下气孔,从而可以减少不必要的机械加工,也为改进工艺操作及时提供信息,最
Introduction Investment casting process is complex, part of the castings require high precision, often after processing because of subcutaneous stomatal, internal slag, trachoma and other defects caused by scrapped, the number sometimes up to 50%. Most of the stomatal defects are 1.5 mm away from the surface and have a diameter of about φ0.5 to φ4 mm and pinholes of less than φ0.5 mm. Stomata were round or oval, more regularly distributed in the castings in the upper part of the gate, a small amount of distribution in other parts of the workpiece. The selection of DC magnetizing flaw detection method can accurately and reliably reflect the subcutaneous pores with a depth of about 5 mm and a diameter of more than 0.5 mm in the casting, thereby reducing unnecessary machining and providing timely information for improving process operation.