铝合金汽车汽缸体局部增压铸造技术研究

Partial Pressurization for Aluminum Alloy Cylinder Body for Automobile by Squeezing Casting

以过共晶B390铝合金汽车汽缸体为对象,研究了挤压铸造-局部增压铸造过程中的增压起始时间和增压压入量对铸件组织的影响。结果表明,通过在汽缸体厚壁热节处设置增压通道实施局部增压,采用10s的增压起始时间和20mm的增压压入量,很好地解决厚壁处易产生缩松、缩孔等缺陷的问题。制造的汽缸体经T6热处理后,铸件抗拉强度、硬度(HB)和伸长率分别达到305MPa、137和4.8%,随机抽取的试样通过了1.38MPa的卤素气体检漏试验。

Effects of pressurization starting time and reduction on microstructure of hypereutectic B390 aluminum alloy cylinder body for automotive were investigated during partial pressurization process by squeezing casting. The results reveal that through employing partial pressurization at hot spot of thick wall position of cylinder body, casting defects, such as shrinkage porosity (hole), easily encountered in thick wall position of the cylinder body can be eliminated with pressurization starting time of 10 s and reduction of 20 mm. Average tensile strength, hardness (HB) and elongation of the cylinder body after T6 heat treatment reach up to 305MPa, 137 and 4.8%, respectively. And the samples picked randomly successfully pass the 1.38MPa halogen gas testing with no leakage.