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Heat resistant magnesium die casting alloys

a technology of heat resistance and die casting alloys, applied in the field of heat resistance magnesium die casting alloys, can solve the problems of not making much progress for parts with bolted parts, reducing the heat resistance of parts, and reducing the heat resistance of conventional die casting magnesium alloys, so as to improve the high temperature strength and castability, and improve the creep resistance

Inactive Publication Date: 2006-10-05
TOYOTA JIDOSHA KK +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0005] The present invention has as its object to provide a heat resistant magnesium die casting alloy simultaneously improved in heat resistance and castability and expanded in range of applications and a die cast product of the same alloy.
[0013] The present invention is characterized by limiting the ratio Ca / Al of the contents of Al and Ca to within a predetermined range so as to improve the combination of the heat resistance and castability over the conventional limits without causing deterioration of characteristics even if adding Al and Ca to high contents considered unsuitable in the past.
[0015] As opposed to this, the inventors newly discovered that by limiting the ratio Ca / Al of the Ca content to the Al content to the range of 0.3 to 0.5, even if adding Al and Ca exceeding the upper limits of the above publication, it is possible to simultaneously achieve an improvement of the high temperature strength and castability, which are the main effects of high Al, and an improvement of the creep resistance, which is the main effect of high Ca, without causing either a drop in the creep resistance due to the higher Al or casting cracks due to the higher Ca. The present invention was completed based on this novel discovery.

Problems solved by technology

However, conventional die casting magnesium alloys greatly deform at high temperatures.
Not much progress has been made for parts having bolted portions exposed to high temperature environments (120° C. or more).
Up until now, various heat resistant magnesium die casting alloys have been developed, but it has not been possible to simultaneously improve the heat resistance (high temperature strength and creep resistance) and castability (hot-cracking resistance and die-sticking resistance during die casting) and therefore the range of application has been limited.
Even with the magnesium alloy of the above proposal, however, it has not been possible to sufficiently cover the range of applications required, so development of a heat resistant magnesium die casting alloy with further improved combination of heat resistance and castability has been desired.

Method used

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  • Heat resistant magnesium die casting alloys
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  • Heat resistant magnesium die casting alloys

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0041] The following experiment was performed to confirm the effect of improvement of the castability and heat resistance by alloy compositions of the present invention.

[0042] Mg alloys of the compositions of Table 1 were die cast under the following conditions using a 135 ton cold chamber die casting machine.

[0043]

[0044] Shape and dimensions of die: 70 w×150 L (3, 2, and 1 t from gate side) . . . flat plate [0045] 15φ×120 L . . . rod

[0046] Die preheating: 200° C.

[0047] Casting temperature: 700 to 720° C.

[0048] Casting atmosphere: 1% SF6+CO2

[0049] The obtained alloy samples were subjected to tensile tests (test temperature: room temperature (RT), 150° C.) and measured for crack length at casting and bolt load retention. As the bolt load retention, the retained bolt load was measured under the following conditions. The measurement results are shown all together in Table 2 and Table 3.

[0050]

[0051] Initial bolt load: 8 kN

[0052] Holding temperature: 150° C.

[0053] Holding time: ...

example 2

[0061] The following experiment was performed to confirm the effect of improvement of the corrosion resistance by RE addition in the alloy composition of the present invention.

[0062] The Mg alloys of the compositions of Table 4 were die cast in the same way as in Example 1. The alloy compositions of No. 101 to 105 shown in Table 4 were basically comprised (target values) of 7% Al-3% Ca-0.5% Sr-0.3% Mn with amounts of RE added (target values) of successively 0% (no addition), 0.1%, 0.5%, 2.0%, and 3.0% (analysis values of added RE elements of 0.08%, 0.44%, 1.77%, and 2.68%). For the RE addition, a Ce-rich (50%) misch metal was used.

[0063] The obtained alloy samples were subjected to salt water spray tests under the following conditions to evaluate the corrosion resistance.

[0064]

[0065] 1. Cut out test piece (width 70 mm×length 50 mm×thickness 3 mm) from the die cast product in the as-cast state.

[0066] 2. Immerse the test piece in acetone and ultrasonically clean it for 15 minutes,...

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Abstract

A heat resistant magnesium die casting alloy simultaneously improved in heat resistance and castability and expanded in range of application is provided. It comprises, includes, by wt %, the following composition: Al: over 6% to not more than 10 %, Ca: 1.8 to 5%, Sr: 0.05 to 1.0%, Mn: 0.1 to 0.6%, and Bal: Mg and unavoidable impurities, the ratio Ca / Al of the Ca content to the Al content being 0.3 to 0.5. To improve the corrosion resistance, 0.1 to 3% of a RE may also be added.

Description

TECHNICAL FIELD [0001] The present invention relates to a heat resistant magnesium die casting alloy and a die cast product of that alloy. BACKGROUND ART [0002] In recent years, to deal with the demand for reduction of the weight of vehicles, greater application of alloys of magnesium, the lightest of the practical metals, has been desired. However, conventional die casting magnesium alloys greatly deform at high temperatures. Not much progress has been made for parts having bolted portions exposed to high temperature environments (120° C. or more). Up until now, various heat resistant magnesium die casting alloys have been developed, but it has not been possible to simultaneously improve the heat resistance (high temperature strength and creep resistance) and castability (hot-cracking resistance and die-sticking resistance during die casting) and therefore the range of application has been limited. [0003] Therefore, to achieve both heat resistance and castability, JP-A-2001-316752 ...

Claims

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Application Information

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IPC IPC(8): C22C23/02B22D17/00B22D21/04
CPCC22C23/02
Inventor HIJII, TAKUMIKITANO, TOMOYASUOHORI, KOICHINAKAURA, YUSUKEMATSUYAMA, HARUTOSHI
Owner TOYOTA JIDOSHA KK