Secondary peak aging method for high-vacuum die-casting high-speed gearbox shell containing rare earth aluminum-silicon alloy

Abstract

A secondary peak aging method for high-vacuum die-casting high-speed gear box shells containing rare earth aluminum-silicon alloys, by placing vacuum die-casting aluminum alloy test rods in a box-type aging furnace, and first heating up to 120°C at a rate of 6‑8°C / s Then keep warm for 20-30min, then continue to heat up at a rate of 4-6°C / s to 240°C, then keep warm for 20-30min, cool down to 210°C at a rate of 3°C / s, keep warm for 3-6 hours, and air-cool after aging. The properties of as-cast test rods were compared under the same casting process. The invention adopts secondary peak aging, and by adding low-cost mixed rare earths, short-term artificial aging at low temperature, controlling time and temperature, enhancing the aging effect, significantly improving the mechanical properties, and avoiding the use of high-temperature solid solution for the high-speed reduction box shell Bubbles and other defects appear on the surface.

Description

technical field [0001] The invention relates to a technology in the field of new energy automobile manufacturing, specifically a secondary peak value of die-casting aluminum alloy with a vacuum degree of 50-100mbar for new energy high-speed gearboxes by adding low-cost mixed lanthanum-cerium rare earth Prescription method. Background technique [0002] Traditional gear box shell casting generally adopts gravity casting, sand casting, etc., and there are often defects such as pores and shrinkage porosity inside. Therefore, during the high-temperature solution treatment process, bubbling and macroscopic deformation will occur on the shell surface, which will affect the shell performance. With the greatly increased torque and speed of new energy vehicles, the whole vehicle puts forward more stringent requirements for the performance and light weight of the high-speed gearbox shell. Therefore, it is necessary to reduce the internal defects of the casting itself through vacuum d...

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Problems solved by technology

[0003] The existing heat treatment process of die-casting aluminum alloy cylinder block often improves the average tensile strength of the cylinder block through high-temperature solid solution and low-temperature aging treatment, but these technologies still cannot avoid the internal defect structure of high-vacuum die-casting cylinder block parts during high-temperature solid solution , such as the expansion of pores and shrinkage cavities, which cannot meet the porosity requirements of the cylinder block, and the problems of bubbling on the surface and remelting at the thin wall

However, the high-speed gearbox shell has very strict requirements on porosity, and bubbling and remelting are prohibited. Therefore, it is difficult to improve the performance of the high-speed gearbox shell by solid solution aging method to meet the requirements of the drawing for porosity.

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