半固态流变压铸Al-20%Si合金充型能力的研究  

Study on Filling Capacity of Semi-Solid Al-20%Si Alloy Prepared by Rheo-Casting

作　　者：钟鼓[1] 吴树森[1] 万里[1] 秦斌[1] 

机构地区：[1]华中科技大学材料成形与模具技术国家重点试验室,湖北武汉430074

出　　处：《铸造》2010年第10期1044-1048,共5页Foundry

基　　金：国家高技术研究发展计划(863计划)项目(2007AA03Z557);国家自然科学基金(50775086)

摘　　要：在合金液相线温度附近,对Al-20%Si高硅铝合金施加高能超声振动,制得具有一定固相率的半固态浆料,并流变压铸成形为蛇形试样。通过正交实验法,研究了压射压力、压射速度和浇注温度对半固态流变压铸Al-20%Si合金充型能力的影响。结果表明,在本试验条件下,工艺参数影响充型能力的强弱依次为:充型压力,压射速度,浇注温度。充型能力随充型压力增大而提高,随压射速度的增大,充型能力先提高后降低。浆料浇注温度在700～680℃间变化时,合金充型流动长度的差别不大。根据正交实验分析,得到最佳充型能力的工艺参数:充型压力为80MPa,充型速度为2.5m/s左右,浆料浇注温度为690℃,流变压铸Al-20%Si半固态合金可达到最大充型长度2118mm。合金的非平衡凝固使得组织中出现了初生α-Al,且试样前端组织较靠近料柄部分更为细小均匀。The semi-solid slurry of Al-20% Si aluminum alloy with certain solid fraction was prepared by the application of ultrasonic vibration near the liquidus temperature of this alloy and then the snake samples were produced by rheo-casting.The effects of injection pressure,injection speed and pouring temperature on filling ability of semi-solid Al-20% Si alloy were investigated through orthogonal test.The results show that the influence of factors above on the filling ability of the alloy from strong to weak are injection pressure,injection speed and pouring temperature.The filling capacity increased with injection pressure,and increased at first and then decreased with injection speed.However,there was little difference among the length of rheo-casted samples while the pouring temperature of slurry changed between 700-680 ℃.According to the analysis of this orthogonal experiment,the maximum filling length 2 118 mm can be achieved with these optimized process parameters：injection pressure of 80 MPa,the injection speed of about 2.5 m/s,and the pouring temperature of slurry at 690 ℃.Considerable primary α-Al appeared because of the semi-solid Al-20%Si alloy solidified in non-equilibrium condition.The microstructure of the sample in front part was finer and more homogeneous than that of part near the gate.

关 键 词：高硅铝合金 超声振动 流变压铸 充型能力 

分 类 号：TG249.2[金属学及工艺—铸造]