Method for producing aluminum-alloy shaped product, aluminum-alloy shaped product and production system

Abstract

The present invention are to provide a method for producing an aluminum-alloy shaped product that exhibits high-temperature mechanical strength superior to that of a conventional aluminum-alloy forged product.The present invention provides a method for producing an aluminum-alloy shaped product, comprising a step of forging a continuously cast rod of aluminum-alloy serving as a forging material, in which the aluminum-alloy contains Si in an amount of 10.5 to 13.5 mass %, Cu in an amount of 2.5 to 6 mass %, Mg in an amount of 0.3 to 1.5 mass % and Ni in an amount of 0.8 to 4%, and satisfies a relational expression of “Ni(% bymass)≧(−0.68×Cu(% by mass)+4.2(% by mass)),and heat treatment and heating steps including a step of subjecting the forging material to pre-heat treatment (82), a step (87) of heating the forging material during a course of forging of the forging material and a step of subjecting an aluminum-alloy shaped product to post-heat treatment (89), said pre-heat treatment (82) including treatment of maintaining the forging material at a temperature of −10 to 480° C. for two to six hours.

Description

TECHNICAL FIELD[0001]The present invention relates to a method for producing an aluminum-alloy shaped product, which method includes a step of forging a continuously cast aluminum-alloy rod serving as a forging material, to an aluminum-alloy shaped product and to a production system for the shaped product.BACKGROUND ART[0002]In recent years, in vehicles such as four-wheel-drive automobiles and two-wheel-drive automobiles (hereinafter such a vehicle will be referred to simply as an “automobile”), attempts have been made to employ an aluminum-alloy forged product in an internal combustion engine piston in order to attain high performance or to cope with environmental regulations. This is because, when such an aluminum-alloy forged product is employed, the weight of driving parts (e.g., a piston) for an internal combustion engine can be reduced, leading to reduction of a load upon operation of the internal combustion engine, enhancement of output, or reduction of fuel consumption. Conv...

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Benefits of technology

[0027]According to the first invention described in (1), since the aluminum-alloy includes Si, Cu, Mg, and Ni, it is possible to obtain shaped products that have excellent high-temperature fatigue strength, forgeability, ductility, and toughness. Further, since the composition of Ni and Cu satisfies a relational expression of Ni(% by mass)≧[−0.68×Cu(% by mass)+4.2(% by mass)], it is possible to improve fatigue strength characteristics at higher temperature.

[0048]More specifically, for example, after aluminum-alloy shaped products are retained at a temperature of 350° C. for 100 hours, the fatigue strength thereof at a temperature of 350° C. becomes 33 MPa or more. These characteristics are, for example, characteristics required for a top surface portion of a piston of an internal combustion engine that comes in contact with a high temperature atmosphere. Accordingly, it is possible to further reduce the thickness of a piston of a conventional internal combustion engine by using the aluminum-alloy shaped product according to the present invention and to reduce the weight of a piston of an internal combustion engine. Further, it is possible to satisfy weight reduction required from the market, and realize to reduce fuel consumption of an internal combustion engine, and to improve output.

Problems solved by technology

However, in the case of such a cast product, difficulty is encountered in reducing internal defects generated during the course of casting, and excess material must be provided on the cast product so as to ensure safety design in terms of strength.

Therefore, when such a cast product is employed in an internal combustion engine piston, reducing the weight of the piston is difficult.

However, high-temperature mechanical characteristics of the cast product are not examined in Patent Document 1.

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