CN1772930A - Modifying process of cast Al-si alloy - Google Patents

Abstract

The present invention is modifying process of cast Al-Si alloy, and belongs to the field of metallurgical structure controlling technology in metal heat treatment. The modifying process of cast Al-Si alloy includes the following steps: smelting cast Al-Si alloy, adding 0.25-2.0 wt% Ce into the mother liquid at 800-850 deg.c, stirring intensely for full reaction, deairing and eliminate slag, maintaining the temperature for 30-60 min, casting, and cooling in the mold to room temperature to obtain the modified cast Al-Si alloy ingot. The modified cast Al-Si alloy ingot has obviously changed microscopic metallurgical structure, homogeneously distributed short rod or granular metallurgical structure, and greatly raised mechanical performance and other advantages.

Description

The rotten method of handling of cast Al-Si alloy

Technical field

The present invention relates to the rotten method of handling of a kind of cast Al-Si alloy, improving its metallographic structure, and improve its mechanical properties, belong to metal heat treatmet processing metallographic control techniques field.

Background technology

Cast Al-Si alloy has advantages such as density is little, specific tenacity is high, plasticity is good and can reuse.Cast Al-Si alloy is widely used in industrial circles such as electric power, automobile and aerospace.

Along with the raising of silicone content, eutectic quantity increases thereupon in the tissue in the hypoeutectic cast aluminium-silicon alloy, though castability improves, occurs a large amount of faller gill shape Eutectic Silicon in Al-Si Cast Alloys in the tissue; Cross eutectic point, the further raising of silicone content, the thick tabular primary silicon of polygon can appear in the transcocrystallized Al-Si alloy, the serious alloy substrate that isolated, and at silicon most advanced and sophisticated mutually and corner angle cause stress concentration, alloy along boundary or the tabular silicon body cracking and the formation crackle of crystal grain, becomes fragile alloy easily, mechanical property particularly plasticity significantly reduces, and the cutting processing performance is variation also.Therefore the cast Al-Si alloy processing of must going bad.By adding alterant, refining eutectic silicon and primary silicon are with lath-shaped or needle-like, that flaky Eutectic Silicon in Al-Si Cast Alloys becomes particulate is long, thick erose primary silicon is become tiny regular shape, follow tissue to change, alloy mechanical performance significantly improves, and machinability also improves.

In conventional at present the production, be that sodium salt and sylvite mix for the most widely used alterant of hypoeutectic al-si alloy.In sodium salt and the sylvite alterant, Cl, F ion pair irony crucible have serious corrosive nature, reduce the work-ing life of crucible; Secondly, sodium, potassium boiling point are low, volatilize easily when high temperature, and metamorphic time is short.Occurred many new rotten methods in recent years again, gone bad as usefulness Sb, Sr, Bi etc.These rotten methods have many good qualities, but some shortcomings are also arranged.The fusing point of Sb is low, and vapour pressure is very big, volatilization in a large number in the time of 700 ℃; Sb and Al can generate infusible compound AlSb, sink to crucible bottom; Sb and Na react the metamorphism of cancelling each other; 6～7 hours rotten working lipe of Sr, but can not use the salt refining.For the transcocrystallized Al-Si alloy alloy, most widely used alterant is a phosphorus.The phosphorus that is usually used at present in the aluminum silicon alloy change agent generally has following several adding form: red phosphorus, microcosmic salt, phosphorated master alloy.The burning-point of red phosphorus is low, and it is serious to be fused to the preceding scaling loss of aluminium liquid, has influence on rotten effect, and emits poisonous gas in the process on the turn, atmosphere pollution, infringement HUMAN HEALTH; Microcosmic salt can produce a large amount of reaction slags in experimentation, aluminium liquid quality is impacted, and reaction vessel such as crucible etc. is had the intensive corrosive nature, is not suitable for widespread use; Cu-P master alloy fusing point is higher, fuse into its effect of performance in the aluminium liquid completely than difficulty, and the scaling loss amount of Cu is very little, is easy to generate segregation after the adding, influences overall performance, should not use under the condition that alloying constituent is had relatively high expectations.

Rare earth element has the physics and the chemical property of a lot of uniquenesses, adds tissue and performance that a spot of rare earth element can greatly influence material.Rare earth element has a lot of active effects in cast Al-Si alloy, mainly be summarised as metamorphism, refining effect, dehydrogenation, refining, cleaning action, alloying action.Rare earth metal has well long-lasting and remelting stability as alterant, and air-breathing tendency is little, and is pollution-free, no corrosive nature.

Summary of the invention

The purpose of this invention is to provide the rotten method of handling of a kind of cast aluminium alloy.

The rotten method of handling of a kind of cast Al-Si alloy of the present invention is characterized in that having following commercial run and step:

A. cast Al-Si alloy is melted through routine, in 800～850 ℃ of temperature ranges, add the rare earth metal Ce of 0.25～2.0wt% ratio in mother liquor, vigorous stirring is fully reacted it subsequently;

B. carry out conventional degasification then, remove slag; Be incubated and cast after 30～60 minutes,, obtain the cast Al-Si alloy ingot casting after rotten the processing then with the mould cool to room temperature.

With the go bad principle of cast Al-Si alloy of rare earth metal cerium (Ce) be: the metamorphism of rare earth element meets adsorption theory, often there is the twin of certain angle to exist at the silicon of unmetamorphosed cast Al-Si alloy in mutually, in the rotten treating processes, rare earth atom is adsorbed in the silicon phase twin groove, all do not pass with the passing at a solid liquid interface, become the foreign atom defective but there is quite a few to embed in the silicon phase lattice, cause lattice distortion.This distortion makes silicon produce twin in more direction, and then tangible metamorphism is arranged.

The advantage of the inventive method is: the alterant consumption is few, and modification effect is obvious, and the anti-burn-out life of alterant is long.The inventive method technology is simple, easy handling; In addition, but equipment is not had corrosive nature and save energy.

Embodiment

After now embodiments of the invention specifically being described in.

Embodiment 1: 1200 gram cast Al-Si alloy A356 are melted through conventional, the rare earth metal Ce that under 850 ℃ of temperature, adds the 0.5wt% ratio to mother liquor, the weight that promptly adds Ce is 6 grams, carry out vigorous stirring subsequently, it is fully reacted, carry out conventional degasification again, remove slag, cast after being incubated 30 minutes then.During casting, adopt metal pattern, metal pattern needs 200 ℃ of preheatings, then with the mould cool to room temperature, and the cast Al-Si alloy ingot casting after obtaining going bad.

Through instrument detecting, obvious variation has taken place in the micro-metallographic structure of the cast Al-Si alloy A356 after rotten the processing, and eutectic structure changes corynebacterium or spherulitic into by thick needle-like or en plaque, and is evenly distributed.Its mechanical property ratio starting ingot improves a lot, and tensile strength is brought up to 188MPa by the 171MPa of starting materials, and unit elongation brings up to 6.6% by 5.7% of starting materials.

Embodiment 2: 1200 gram cast Al-Si alloy Al-14.5Si alloys are melted through conventional, the rare earth metal Ce that under 830 ℃ of temperature, adds the 0.5wt% ratio to mother liquor, the weight that promptly adds Ce is 6 grams, carry out vigorous stirring subsequently, it is fully reacted, carry out conventional degasification again, remove slag, cast after being incubated 30 minutes then.During casting, adopt metal pattern, metal pattern needs 200 ℃ of preheatings, then with the mould cool to room temperature, and the cast Al-Si alloy ingot casting after obtaining going bad.

Through instrument detecting, obvious variation has taken place in the micro-metallographic structure of the cast Al-Si alloy Al-14.5Si after rotten the processing, the primary silicon size reduces than starting ingot is obvious, is evenly distributed, and eutectic structure becomes corynebacterium or spherulitic by thick needle-like or en plaque.Its mechanical property ratio starting ingot improves a lot, and tensile strength is brought up to 147MPa by the 132MPa of starting materials, and unit elongation brings up to 2.5% by 1.4% of starting materials.

Embodiment 3: the preparation process of present embodiment and step and embodiment 1 are identical.Different is that the cast Al-Si alloy that adopts is the Al-18Si alloy.

Through instrument detecting, obvious variation has taken place in the micro-metallographic structure of the cast Al-Si alloy Al-18Si alloy after rotten the processing, primary silicon changes regular shape into by thick irregular polygon, size obviously reduces, and be evenly distributed, eutectic structure becomes corynebacterium or spherulitic by thick needle-like.Its mechanical property ratio starting ingot improves a lot, and tensile strength is brought up to 91MPa by the 62MPa of starting materials, and unit elongation brings up to 3.2% by 2.4% of starting materials.

Embodiment 4: the preparation process of present embodiment and step and embodiment 1 are identical.Different is: added the rare earth metal Ce of 1.0wt% ratio in mother liquor A356, the weight that promptly adds Ce is 12 grams.

Through instrument detecting, obvious variation has taken place in the micro-metallographic structure of the cast Al-Si alloy A356 after rotten the processing, and eutectic structure changes corynebacterium or spherolite into by thick needle-like or en plaque, and is evenly distributed.Its mechanical property ratio starting ingot improves a lot, and tensile strength is brought up to 185MPa by the 171MPa of starting materials, and unit elongation brings up to 6.8% by 5.7% of starting materials.

Embodiment 5: the preparation process of present embodiment and step and embodiment 1 are identical.Different is: added the rare earth metal Ce of 2.0wt% ratio in mother liquor A356, the weight that promptly adds Ce is 24 grams.

Through instrument detecting, obvious variation has taken place in the micro-metallographic structure of the cast Al-Si alloy A356 after rotten the processing, and eutectic structure changes corynebacterium or spherolite into by thick needle-like or en plaque, and is evenly distributed.Its mechanical property ratio starting ingot also has raising, and tensile strength is brought up to 182MPa by the 171MPa of starting materials, and unit elongation brings up to 6.2% by 5.7% of starting materials.

Claims (1)

1. the rotten method of handling of a cast Al-Si alloy is characterized in that having following commercial run and step:

A. cast Al-Si alloy is melted through routine, in 800～850 ℃ of temperature ranges, add the rare earth metal Ce of 0.25～2.0wt% ratio in mother liquor, vigorous stirring is fully reacted it subsequently;

B. carry out conventional degasification then, remove slag; Be incubated and cast after 30～60 minutes,, obtain the cast Al-Si alloy ingot casting after rotten the processing then with the mould cool to room temperature.