AlSi7Mg alloy has been widely used in aerospace and automotive industry due to its excellent formability, high corrosion resistance and good comprehensive mechanical properties. Because of its excellent mechanical properties and good lightweight effect, it has more and more applications in automobile structural parts. At the same time, as a rapid near-net molding casting process, high-pressure casting is particularly suitable for the design and molding of such structural parts. However, there are still defects and unstable mechanical properties in the production process of aluminum alloy die castings.
Taking an AlSi7Mg part as the research object, the die-casting production of AlSi7Mg alloy automobile test pieces was carried out with different pouring temperatures and mold preheating temperatures, and the mechanical properties of the test pieces under different parameters were tested and the X-ray nondestructive testing results were studied, It is expected to provide technical reference for the industrial production of AlSi7Mg alloy die castings.
(1) Adding 0.008%~0.015% Ce to SUS444 ferritic stainless steel can change the type, shape and size of inclusions while purifying the steel quality. 0.008% Ce is not enough to completely modify SiO2, 0.015% Ce can achieve complete modification of inclusions, and can transform large size and irregular shape SiO2 into small size spherical Ce2O3 inclusions.
(2) A trace of 0.008% ～ 0.015% Ce can significantly refine the microstructure of SUS444 ferritic stainless steel, improve the yield strength and tensile strength of stainless steel, and increase the maximum by 15%, so that the tensile fracture is completely transformed from ductile brittle fracture to ductile fracture; The impact toughness was significantly improved, up to 4.9 times, and the impact fracture changed from brittle fracture to ductile fracture.
(3) Inclusion modification and microstructure refinement are the main reasons for improving the mechanical properties of SUS444 stainless steel. Considering the inclusion and mechanical properties comprehensively, the optimum Ce content in stainless steel is 0.015%, which can be used to prepare rare earth type high-strength and ductile ferritic stainless steel.