TiAl基合金排气阀金属型离心铸造过程内部缺陷分析

在所建立的数学模型基础上总结了TiAl基合金熔体离心力场下的充型规律.结果表明,离心力场的施加对于充型过程有重要影响,熔体以变化的截面面积和倾角填充铸型.熔体截面面积随充型长度的增大而减小,而熔体截面倾角随充型长度的增大而增大,这种变化在型腔入口附近表现得更加明显.此外,针对金属型离心浇铸Ti-48Al-2Cr-2Nb (at%) 合金汽车排气阀内部的常见缺陷,探讨了离心力场下排气阀内部卷入性气孔和偏中心线缩松的产生机理.

Analysis on inner defects in TiAl based alloy exhaust valve during the centrifugal foundry process in permanent mold

The filling rules of TiAl based alloy melt in centrifugal field has been concluded basing on the mathematical model. Results show that centrifugal field has an important influence on the filling process and melt fills the mould with variational cross section and inclined angle. Cross section area decreases and inclined angle increases respectively when filling length increases, and the change becomes more obviously near the entrance. In addition, the forming reasons of entrapping poles and prejudicial shrinkage existing in the TiAl based alloy valves poured in permanent mould during the centrifugal casting process have been discussed.