不锈钢铸造中产生气孔的主要原因
Main causes of gas hole production in stainless steel casting
1、涂料的透气性差或者负压不足，充填砂的透气性差，不能及时排出型腔内的气体及残留物，在充型压力下形成气孔。
1, the air permeability of the coatings is poor or the negative pressure is insufficient, and the air permeability of the filling sand is poor, so that the gas and residues in the cavity can not be discharged in time, and stomata form under the filling pressure.
2、浇注速度太慢，未能充满浇口杯，暴露直浇道，卷入空气，吸入渣质，形成携裹气孔和渣孔。
2, the casting speed is too slow, can not fill the gate cup, exposes the straight gate, gets involved in the air, inhales the slag, forms the bag and the slag hole.
3、泡沫模型气化分解生成大量的气体及残留物不能及时排出铸型，泡沫、涂料层填充干砂的干燥不良，在液态合金的高温包围下，裂解出大量的氢气和氧气侵入铸件是形成气孔的主要原因。
3, the bubble model gasification decomposition to generate large amounts of gas and residue can be discharged in time to cast, foam, paint layer filling sand dry bad, surrounded by high temperature liquid alloy, a large number of hydrogen cracking and oxygen into the casting is the main reason for the formation of pores.
4、由于浇注系统设计不合理，金属液的充型速度大于泡沫气化退让及气体排出速度，造成充型前沿将气化残留物包夹在金属液体中再次气化形成内壁烟黑色的分解气孔。
4, due to the unreasonable design of gating system, the filling speed of metal liquid is greater than that of foam gasification and gas discharge. The filling front will cause the gasification residue to be encapsulated in metal liquid again to form a decomposed hole of smoke black inside the wall.