High strength aluminum alloy casting and method of production of same

Abstract

A high strength aluminum alloy casting obtained by casting an aluminum alloy comprised of 7.5 to 11.5 wt % of Si, 3.8 to 4.8 wt % of Cu, 0.45 to 0.65 wt % of Mg, 0.4 to 0.7 wt % of Fe, 0.35 to 0.45 wt % of Mn, and the balance of Al and not more than 0.2 wt % of unavoidable impurities, wherein this aluminum alloy has 0.1 to 0.3 wt % of Ag added to it or contains 0.1 to 1.0 wt % of at least one element selected from the group of second additive elements comprised of Rb, K, Ba, Sr, Zr, Nb, Ta, V, and Pd and rare earth elements, and a method of production of a high strength aluminum alloy casting comprising the steps of filling a melt of an aluminum alloy in a mold to obtain a casting, taking out the aluminum alloy casting from the mold, solubilizing the high strength aluminum alloy casting by heating in a temperature range of 495 to 505° C. for 2 to 6 hours, quenching the high strength aluminum alloy casting after the solubilization, and age hardening the high strength aluminum alloy casting by heating in a temperature range of 160 to 220° C. for 2 to 6 hours after quenching.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a high strength aluminum alloy casting having superior mechanical properties, a high strength aluminum alloy casting including a neutralizing casting defect element for increasing the strength (hereinafter also referred to as an “NCDE”), and parts made from this high strength aluminum alloy casting such as a scroll for a compressor for an air-conditioner, a vane rotor of a valve timing regulating device, and a housing of an antilock braking system. Further, the present invention relates to a method of production of the above high strength aluminum alloy casting, a method of production of a high strength aluminum alloy casting including a neutralizing casting defect element, and a method of production of parts made from this high strength aluminum alloy casting such as a scroll for a compressor of an air-conditioner, a vane rotor of a valve timing regulating device, and a housing of a...

AI Technical Summary

Benefits of technology

[0006] An object of the present invention is to provide a high strength aluminum alloy casting keeping down capital costs, raising productivity, extending the lifetime of the casting or die casting mold, and reducing the cost of the product. Another object of the present invention is to provide a high strength aluminum alloy casting improving the tensile strength, yield strength, fatigue strength, etc. of the aluminum alloy casting, reducing casting defects, and increasing the fineness of dispersion of the structure. Still another object of the present invention is to provide a scroll for an air-conditioner, a vane rotor of a valve timing regulating device, and a housing of an antilock braking system made from this high strength aluminum alloy casting. A still further object of the present invention is to provide a method of production of this high strength aluminum alloy casting.

[0009] Preferably, an amount of gas included in the high strength aluminum alloy casting is kept to not more than 1.5 cm3 with respect to 100 g of the high strength aluminum alloy casting, and solubilization and age hardening are performed to enhance the strength.

[0010] Preferably, when casting or die casting, the rare earth element reacts with molten hydrogen in the aluminum alloy to form a compound and suppress casting defects arising due to the molten hydrogen.

[0017] Alternatively, the method of production is a die cast method and further comprises the step of closing mold halves, pouring aluminum melt into a melt sleeve of a die cast machine, then using low speed die casting to fill high strength aluminum alloy into the mold while advancing an injection plunger at a low speed so as to keep air and heat decomposition gas produced from a release agent etc. from being entrained.

[0019] A method of production of a scroll for a compressor of an air-conditioner made from a high strength aluminum alloy casting, comprising the steps of reducing the pressure inside the mold to not more than 13.3 kPa and filling the mold with a high strength aluminum alloy after reduction of pressure for die casting.

Problems solved by technology

Further, in the method of production, it was confirmed that the tensile strength, yield strength, and fatigue strength of the die castings were enhanced, but these aluminum alloy die castings have casting structures formed as meshes, so were inferior in properties compared with aluminum alloy die castings solubilized and age hardened to make the eutectic Si spherical (T6 treatment).

With just the improvements of the method of production described in Japanese Unexamined Patent Publication (Kokai) No. 2000-192180, it is not possible to satisfy the design requirements of aluminum alloy scrolls.

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