CN103343248A - Application of Al-Ti-C-Sr refiner in A356.2 aluminum knuckle of automobile - Google Patents

Abstract

The invention relates to application of an Al-Ti-C-Sr refiner in an A356.2 aluminum knuckle of an automobile. The technique comprises the following processing steps: (1) smelting and refining; and (2) carrying out low-pressure casting and thermal treatment. The defects of insufficient refining of crystal particles and low performance or the defects of high price of an Al-Ti-B refiner and the like when the traditional refiner and alterant are applied to the A356.2 automobile knuckle are mainly solved. Just intermediate alloy of the refiner Al-Ti-B is independently added, and then the Sr alterant is added in the international automotive industry at present. Thus, an A356.2 alloy structure is changed by using the Al-Ti-C-Sr refiner; the refiner not only can play a role of refining the crystal particles, but also can play a role of deterioration, and the roles of refining eutectic silicon and refining the structure; the strength, the plasticity and the corrosion resistance of the alloy can be improved.

Description

The Al-Ti-C-Sr fining agent is in the application of A3562 automobile aluminum products steering knuckle

Technical field

The present invention relates to the Al-Ti-C-Sr fining agent in the application of A356.2 alloy, particularly a kind of Al-Ti-C-Sr fining agent is in the application of A356.2 automobile aluminum products steering knuckle.

Background technology

Spindle is one of major part on the steering axle of automobile, belongs to automotive security spare.The effect of steering knuckle is to bear automotive front load, and supporting and drive front-wheel make motor turning around stub rotates.Under motoring condition, it is bearing changeable shock load, therefore, requires it to have very high intensity.Present international automobile industry, often adopt the A356 alloy to make steering knuckle, A356 belongs to hypoeutectic structure, Si mass content 〉=6%, so adopt various rotten processing, usually adopt Sr rotten, for crystal grain thinning often adds Al-Ti or Al-Ti-B fining agent, improve alloy structure and performance like this.And the TiAl3 phase of thick needle-like may appear when adding Al-Ti, there is TiB2 that the tendency of gathering is arranged and add the Al-Ti-B fining agent, be unfavorable for the bigger raising of alloy strength and plasticity like this, steering knuckle body tensile strength Rm=300Mpa, yield strength Rp0.2=228Mpa, unit elongation A=9% that traditional method is made.Can satisfy tensile strength Rm 〉=290Mpa, yield strength Rp0.2 〉=220Mpa, unit elongation A 〉=8% requirement like this, but intensity not very high, and Al-Ti-B master alloy cost costliness.

Summary of the invention

The object of the present invention is to provide a kind of Al-Ti-C-Sr fining agent in the application of A356.2 automobile aluminum products steering knuckle, it mainly solves existing fining agent and alterant crystal grain thinning deficiency, the low shortcoming of performance when the A356.2 spindle is used, perhaps use shortcomings such as the Al-Ti-B fining agent is expensive, and the international automobile industry just adds fining agent Al-Ti-B master alloy separately at present, is adding the Sr alterant then; The present invention adopts the Al-Ti-C-Sr fining agent that the A356.2 alloy structure is changed, and this fining agent not only can crystal grain thinning but also played metamorphism, makes the Eutectic Silicon in Al-Si Cast Alloys refinement, and the effect of structure refinement can improve alloy strength, plasticity and erosion resistance.

The present invention solves the problems of the technologies described above the technical scheme that adopts.

A kind of Al-Ti-C-Sr fining agent is in the application of A356.2 automobile aluminum products steering knuckle, and it is characterized in that: it comprises the steps:

(1) melting and refining

99.99% fine aluminium, 99.99% pure magnesium, Al-Si24, Al-5Ti-C-0.8Sr master alloy are adopted in the alloy preparation, adopt the crucible resistance melting, smelting temperature 750-760 ℃, and under this temperature, be incubated 40 minutes, guarantee that material melts fully, subcontract in the importing, after add refining agent N ₂Degasification, static 15 minutes, to survey hydrogen and make density import 〉=2.62, concrete composition proportion according to the form below imports aluminium liquid in the holding furnace after the test passes;

Composition	Si	Fe	Cu	Mn	Mg	Zn	Ti	Sr	Al
										Weight %	6.5-7.5	0.15	0.10	0.10	0.30-0.45	0.10	0.10-0.25	0.012-0.025	Surplus

(2) low-pressure casting and thermal treatment

Low-pressure casting: temperature of aluminum liquid 710-720 ℃; 320 ℃ of patrix temperature, 260 ℃ of counterdie temperature; The pressure setting means be one section pressure rising time 12S, pressure 190mbar, two sections pressure rising time 20S, pressure 300mbar, three sections pressure rising time 3S, pressure 550mbar, four sections pressure rising time 2S, pressure 650mbar, five sections pressure rising time 1S, pressure 700mbar, dwell time 3min, pressure 700mbar solidifies the 50S pressure release;

Thermal treatment process: quenching technology: from being warmed up to 420 ℃ of heating-up time 2.5H below 200 ℃, to 420 ℃ of insulation 2H, be warmed up to 540 ℃ of heating-up time 0.5H from 420 ℃ again, to 540 ℃ of insulation 6H, back water-cooled, quenching 15S transfer time, 40 ℃ of water temperatures.Aging technique: 155 ℃ of aging temps, aging time 6H.

Use the Al-Ti-C-Sr fining agent to join A356.2 aluminum steering knuckle tensile strength Rm=317Mpa, yield strength Rp0.2=240Mpa, unit elongation A=10% among the present invention, can satisfy steering knuckle higher-strength and plasticity requirement, and have high weather resistance and erosion resistance, can make the present invention be widely used in the production of aluminum steering knuckle security part like this.And a kind of alloy structure that improves is provided, improve the way of alloy strength and plasticity.

Description of drawings

Fig. 1 is the as-cast condition metallographic structure figure during the present invention uses.

Fig. 2 is the as-heat-treated condition metallographic structure figure during the present invention uses.

Embodiment

The invention discloses the Al-Ti-C-Sr fining agent in the application of A356.2 automobile aluminum products steering knuckle, particularly the Al-Ti-C-Sr fining agent mainly is that it can improve alloy strength, plasticity and corrosion resistance nature effect in the effect of A356.2 alloy.

Below further introduce the Al-Ti-C-Sr fining agent in the application of A356.2 automobile aluminum products steering knuckle by an embodiment.The concrete technological process of production comprises the steps:

(1) melting and refining

99.99% fine aluminium, 99.99% pure magnesium, Al-Si24, Al-5Ti-C-0.8Sr master alloy are adopted in the alloy preparation, adopt the crucible resistance melting, 759 ℃ of smelting temperatures, and under this temperature, be incubated 40 minutes, guarantee that material melts fully, subcontract in the importing, temperature of aluminum liquid adds refining agent and uses N at 723 ℃ ₂Degasification, static 15 minutes, survey hydrogen density 〉=2.62, concrete composition proportion must satisfy shown in the following table, after the test passes aluminium liquid is imported in the holding furnace, can cast.

Composition	Si	Fe	Cu	Mn	Mg	Zn	Ti	Sr	Al
										Standard %	6.5-7.5	0.15	0.10	0.10	0.30-0.45	0.10	0.10-0.25	0.012-0.02	Surplus
Actual measurement %	7.1	0.1	0.05	0.10	0.35	0.10	0.15	0.016	Surplus

(2) low-pressure casting and thermal treatment process

Low-pressure casting: 716 ℃ of temperature of aluminum liquid; 320 ℃ of patrix temperature, 260 ℃ of counterdie temperature; Pressure set (one section pressure rising time 12S, pressure 190mbar, two sections pressure rising time 20S, pressure 300mbar, three sections pressure rising time 3S, pressure 550mbar, four sections pressure rising time 2S, pressure 650mbar, five sections pressure rising time 1S, pressure 700mbar, dwell time 3min, pressure 700mbar solidifies the 50S pressure release).

Thermal treatment process: quenching technology: from being warmed up to 420 ℃ of heating-up time 2.5H below 200 ℃, to 420 ℃ of insulation 2H, be warmed up to 540 ℃ of heating-up time 0.5H from 420 ℃ again, to 540 ℃ of insulation 6H, back water-cooled, quenching 15S transfer time, 40 ℃ of water temperatures.Aging technique: 155 ℃ of aging temps, aging time 6H.

Carry out quality examination control according to above-mentioned technology, metallographic structure, performance test detect.

Metallographic structure

From as-cast condition undertissue (Fig. 1): dendritic network is tiny, be evenly distributed, and the about 25 μ m of dendrite interval,, the tiny point-like that is of Eutectic Silicon in Al-Si Cast Alloys is evenly distributed.Refinement and going bad is described.Tissue (Fig. 2) after the thermal treatment: remelt eutectic spheroid, coarse-grain circle and part all do not occur and be fusiform and crystal boundary hair, triangle crystal boundary or along crystal boundary quenching crack phenomenon, not burning or superheating phenomenon.

Performance test

Room temperature tensile performance and Brinell hardness test result see the following form

Above-mentioned every test result all satisfies product requirement, and the thermal treatment process that the Al-Ti-C-Sr fining agent changes the A356.2 alloy structure and the present invention adopts can guarantee that product satisfies the use properties requirement.

Superiority of the present invention and positive effect are:

1, adopt the Al-Ti-C-Sr fining agent that the A356.2 alloy structure is changed, equally distributed TiAl3 also effectively prevents the loose gathering of TiC compound in this fining agent, not only improves the thinning effect of fining agent, the about 25 μ m of dendrite interval.And improve the alloy casting formability greatly, effectively improve the plasticity of alloy simultaneously; This fining agent contains the Sr element can play metamorphism, makes the Eutectic Silicon in Al-Si Cast Alloys refinement, has the effect that improves intensity and plasticity.

2, the alloy after the Al-Ti-C-Sr fining agent is handled is evenly tiny, impels to a great extent in the alloying element disperse distribution aluminum substrate, is conducive to improve alloy strength like this.

3, the Al-Ti-C-Sr fining agent joins in the A356.2 material and makes steering knuckle, (be quenching technology: from being warmed up to 420 ℃ of heating-up time 2.5H below 200 ℃ through Overheating Treatment, to 420 ℃ of insulation 2H, be warmed up to 540 ℃ of heating-up time 0.5H from 420 ℃ again, to 540 ℃ of insulation 6H, back water-cooled, 15S transfer time that quenches, 40 ℃ of water temperatures.Aging technique: 155 ℃ of aging temps, aging time 6H.) back its intensity and plasticity all can reach the technical requirements of steering knuckle.

In sum, be preferred embodiment of the present invention only, be not to limit practical range of the present invention, i.e. all equivalences of doing according to the content of the present patent application claim change and modify, and all should be technology category of the present invention.

Claims (1)

1. an Al-Ti-C-Sr fining agent is in the application of A356.2 automobile aluminum products steering knuckle, and it is characterized in that: it comprises the steps:

(1) melting and refining

99.99% fine aluminium, 99.99% pure magnesium, Al-Si24, Al-5Ti-C-0.8Sr master alloy are adopted in the alloy preparation, adopt the crucible resistance melting, smelting temperature 750-760 ℃, and under this temperature, be incubated 40 minutes, guarantee that material melts fully, subcontract in the importing, after add refining agent N ₂Degasification, static 15 minutes, to survey hydrogen and make density import 〉=2.62, concrete composition proportion according to the form below imports aluminium liquid in the holding furnace after the test passes;

Composition Si Fe Cu Mn Mg Zn Ti Sr Al Weight % 6.5-7.5 0.15 0.10 0.10 0.30-0.45 0.10 0.10-0.25 0.012-0.025 Surplus

(2) low-pressure casting and thermal treatment

Low-pressure casting: temperature of aluminum liquid 710-720 ℃; 320 ℃ of patrix temperature, 260 ℃ of counterdie temperature; The pressure setting means be one section pressure rising time 12S, pressure 190mbar, two sections pressure rising time 20S, pressure 300mbar, three sections pressure rising time 3S, pressure 550mbar, four sections pressure rising time 2S, pressure 650mbar, five sections pressure rising time 1S, pressure 700mbar, dwell time 3min, pressure 700mbar solidifies the 50S pressure release;

Thermal treatment process: quenching technology: from being warmed up to 420 ℃ of heating-up time 2.5H below 200 ℃, to 420 ℃ of insulation 2H, be warmed up to 540 ℃ of heating-up time 0.5H from 420 ℃ again, to 540 ℃ of insulation 6H, back water-cooled, quenching 15S transfer time, 40 ℃ of water temperatures.Aging technique: 155 ℃ of aging temps, aging time 6H.

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