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研究了挤压铸造A356.2铝合金螺簧座的力学性能和微观组织,对其进行了充型以及凝固模拟,探讨了断口集中于试样下部的原因。结果表明,铸态螺簧座本体取样的抗拉强度、屈服强度、伸长率分别为268 MPa、184 MPa、9.3%;T6处理后达到330 MPa、266 MPa、6.4%。在一定范围内,随着充型速度和铸造压力的增加,抗拉强度和伸长率都有较为明显的提高,但对屈服强度影响不大。挤压铸造条件下,α-Al相可使晶粒细化并使其呈团块状发展,但对亚共晶相影响很小。在螺簧座底部、中部和上部均有涡流产生,凝固时会在拐角处产生热节,有缩孔、缩松倾向。试样的断裂位置集中在弹簧座下部,是涡流导致的夹杂物与卷气共同作用的结果,可以通过对充型速度采用分段变速法来解决。
The mechanical properties and microstructure of squeeze cast A356.2 aluminum alloy reed seat were investigated. The filling and solidification simulation of the reformed aluminum was carried out. The reason why the fracture was concentrated in the lower part of the sample was discussed. The results show that the tensile strength, yield strength and elongation of as-cast bulkhead specimens are 268 MPa, 184 MPa and 9.3% respectively, and reach 330 MPa, 266 MPa and 6.4% after T6 treatment. Within a certain range, with the increase of filling speed and casting pressure, the tensile strength and elongation increased obviously, but had little effect on the yield strength. Under the conditions of squeeze casting, the α-Al phase can refine the grain and make it grow into a lump, but it has little effect on the hypoeutectic phase. In the spring seat at the bottom, the middle and upper part of the vortex are generated, solidification will produce heat in the corner, there are shrinkage, shrinkage tendency. The fracture location of the sample is concentrated in the lower part of the spring seat, which is the result of the co-action of the inclusions and the air entrainment caused by the vortex flow. This can be solved by adopting a piecewise variable speed method on the filling speed.