超声场作用下Mg-3Ca合金除气及细化的工艺研究

Study on Degassing and Refining Technology of Mg-3Ca Alloy under Ultrasonic Field

对Mg-3Ca合金熔体进行超声处理来研究超声功率、施振时间和施振温度对合金除气及凝固组织的影响。结果表明,采用超声波处理技术,可以有效去除Mg-3Ca合金熔体中的气体,从而提高铸锭的致密度。超声除气效果与施振功率、处理时间及处理温度密切相关。当施振功率过小、处理时间过短或过长及处理温度过高或过低均不会有良好的除气效果。熔体处理温度为:700℃,超声功率为150W,处理时间为120s时除气效果最好,除气率可达53.8%。另外,超声波在去除熔体中气体的同时,也使得铸锭的凝固组织变得细小、均匀。粗大的树枝晶不利于气泡的上浮和熔体补缩;而均匀、细小的等轴晶则有利于这一点。

The effects of ultrasonic power,duration and treatment temperature on molten Mg-3Ca alloy degassing and solidification structure were investigated.The results indicate that applying of ultrasonic treatment technology can effectively remove gas and increase the density of Mg-3Ca alloy.Ultrasonic degassing effect is closely related with ultrasonic power,duration and treatment temperature.Too low ultrasonic power,too short or too long ultrasonic duration and too high or too low temperature are not beneficial to degassing effect.Under this experiment condition,when ultrasonic power is 150 W,ultrasonic duration is 120 s and treatment temperature is 700 ℃,the optimum degassing effect can be obtained and the degassing efficiency reaches 53.8%.In addition,ultrasound not only removes gas in melt,but also obtains the uniform refining solidification structure of ingot at the same time.Coarsened dendrite is adverse to bubbles rising and melt feeding.However,uniform refining equiaxed grain is beneficial to bubbles rising and melts feeding.