A356.2铝合金螺簧座挤压铸造工艺的研究

Microstructure and Mechanical Properties of Squeeze Casting A356.2 Spring Seat

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。

Mechanical properties and microstructure of squeezing casting A356.2 spring seat were investi-gated,and the filling and solidification were simulated by the Anycasting software.Meanwhile,the phe-nomenon of tensile fractures concentrated on the bottom of the samples was described by the Anycasting software.It is found that the tensile strength,yield strength and elongation of as-cast samples reach 268 MPa and 184 MPa,9.3% ,respectively,and after T6 treatment,the mechanical properties of the spring seat reach 330 MPa and 266 MPa,6.4% ,respectively.Within a certain range,with the increase of the filling speed and casting pressure,tensile strength and elongation are increased,while change of yield strength can be ignored.After squeeze casting,α-Al phase in the spring seat is refined and tends to ag-glomeration,however,little impact on the eutectic phase can be observed.The filling and solidification simulation results show that there are three eddy distributed in the bottom,middle and upper of spring seat,and hot spot at the corner of spring seat can be observed,leading to the possible occurrence of shrinkage porosity.The tensile fractures concentrated on the bottom of the samples is attributed to coac-tion of inclusions and gas involved,which can be eliminated by sectionally changing velocity technique.