Effects Of Ultrasonic Assisted Degassing Methods In Aluminum Melt On Ingot Defects

Initial hydrogen content in the melt before solidification had a great impact on the solidified organizations’defects and performance, especially ingot casting’s stoma,porosity,cracks and density, strength.The main researches of this paper were shown as follows:1.According to the experiments, we analyzed the degassing efficiency in several groups of chloride, ultrasonic, ultrasonic assisted chloride degassing; inert gas, ultrasonic assisted inert gas degassing; stirring, ultrasonic assisted stirring degassing. The results showed that:1%chloride degassing efficiency was18.6%, ultrasonic(applied10min) degassing efficiency was45.7%, and ultrasonic assisted chloride degassing efficiency was47.2%,increased153.7%and3.3%respectively. The inert gas degassing efficiency wad up to40.1%, and ultrasonic assisted inert gas degassing efficiency was56.7%, increased41.4%.Under the stirring situation, if the mixing speed was lower than150r/min or the mixing time was less than6min, the hydrogen content in the melt would have a slight decreased, the maximal degassing efficiency was6.3%and3.6%, and ultrasonic assisted stirring degassing efficiency was38%.2. The critical hydrogen content of porosity generation was improved by ultrasonic, and then suppress the holes’generation. The experiments results showed that:The critical hydrogen content under chloride far less than0.240ml/100g(Al), the critical hydrogen content of ultrasonic assisted chloride was0.226ml/100g(Al); the critical hydrogen under inert gas and ultrasonic assisted inert gas situation was0.226ml/100g(Al) and0.248ml/100g(Al) respectively; the critical hydrogen of stirring did not have a specific value, and the ultrasonic assisted stirring’s critical hydrogen content was0.190ml/100g(Al).3. The ingots’microscopic shrinkage was improved because of ultrasonic. Considering the cracks, the combination of Mg-H increased the cracking susceptibility between the grain boundaries.we found that the distribution of Mg in the grain boundaries would be influenced by ultrasonic,and Mg distribution between boundaries and crystal grain tended to be uniform, the Mg segregation of ultrasonic on boundaries and crystal grain had lower than no ultrasonic group, The ratio of no ultrasonic group was3.031, and the ultrasonic group was1.989, ultrasonic weakened the combination of Mg-H,then declined the cracking susceptibility...