以 ADC12铝合金为原料，采用近液相线挤压铸造生产汽车铝合金支架，研究近液相线挤压铸造技术工艺参数对汽车承力件铝合金支架组织及力学性能的影响。结果表明：近液相线挤压铸造可获得均匀细小的球状组织。在595到625℃的浇注温度范围内，球状组织逐渐长大为蔷薇状晶及树枝晶，球状系数降低，晶粒尺寸升高，抗拉强度及伸长率均有所降低。在断口分析中，韧窝的数量减少，解理面的数量增多；随着压强由90 MPa上升到180 MPa，球状晶生长时间逐渐减少，最后以球状晶形式存在，球状系数升高，晶粒尺寸减小，抗拉强度及伸长率逐渐升高；随着保压时间从10 s延长到25 s，抗拉强度及伸长率有所增加。近液相线挤压铸造的最佳工艺为：浇注温度为605℃、压力为150 MPa、保压时间为20 s。由于铝液的流动，球状晶长大成孪生的蔷薇状晶。%The effect of near liquidus squeeze casting (NLSC) process on microstructure and mechanical properties of ADC12 alloy differential support was investigated. The results show that uniform globular crystals are obtained by NLSC. With the pouring temperature increasing from 595 to 625 ℃, the globular crystals grow into rosette crystals or dendrites, the average globular coefficient (AGC) decreases and the average grain size (AGS) increases, leading to a reduction of tensile strength and elongation. The dimple quantity decreases, meanwhile, the quantities and areas of cleavage planes increases in fracture appearance. With the increase of pressure from 90 to 180 MPa, AGC increases and AGS decreases, leading to an increase of tensile strength and elongation. As the holding time increases from 10 to 25 s, the tensile strength and elongation increase slightly. The optimal parameters of NLSC process are pouring temperature of 605 ℃, pressure of 150 MPa and holding time of 20 s. The globular crystals grow to the twin rosette crystals easily due to the flow of metal.
展开▼
