真空低压消失模壳型铸造和消失模铸造铝合金组织和性能对比

Comparison of microstructures and properties of aluminum alloy between expendable pattern shell casting with vacuum and low-pressure and lost foam casting

利用光学显微镜(OM)、扫错电镜(SEM)等对真空低压消失模壳型铸造和消失模铸造A356铝合金的组织和性能进行对比分析。结果表明:真空低压消失模壳型铸造A356铝合金组织比消失模铸造A356铝合金组织细小、致密,其初生相晶粒尺寸和共晶硅尺寸都远小于消失模铸造铝合金的,孔隙率低于消失模铸造铝合金的、密度高于消失模铸造铝合金的。真空低压消失模壳型铸造A356合金的拉伸断裂方式以韧性断口为主,消失模铸造铝合金的断裂方式以脆性断口为主;铸件经T6热处理后的抗拉强度、伸长率和布氏硬度分别达到278.27 MPa、8.10%和93.1HB,较消失模铸件的分别提高了20.2%、166.4%和17.6%;其铸件表面质量也优于消失模铸件的表面质量。

The microstructures and properties ofA356 alloy produced using expendable pattern shell casting process with vacuum and low-pressure （EPSC-VL） were compared with those of lost foam casting （LFC） process by OM and SEM techniques. The results show that microstructure of A356 alloy produced by EPSC-VL is finer and denser than that of LFC, and the sizes of the primary phase and eutectic silicon are far less than those of LFC, its porosity is less than that of LFC, and its density is higher than that of LFC. The fracture mechanism of A356 alloy obtained using EPSC-VL mainly shows ductile fracture, and that of A356 alloy obtained using LFC mainly shows brittle fracture. The tensile strength, elongation as well as hardness of A356 after T6 treatment alloy fabricated using EPSC-VL are respectively 278.27 MPa, 8.10% and 93.1HB, and are respectively 20.2%, 166.4% and 17.6% higher than those of LFC. Furthermore, the surface roughness of castings made by EPSC-VL is better than that of LFC.