Metamorphic process of hypo eutectic casting aluminum-silicon alloy

Abstract

The invention discloses a metamorphic process of a hypo eutectic casting aluminum-silicon alloy, which comprises the steps of: 1) dosing according to components of the hypo eutectic casting aluminum-silicon alloy; 2) cleaning, drying and placing the alloy and an intermediate alloy into a crucible resistance furnace which is 5kW in power, heating till completely being melted, and controlling the temperature of the melt at 700+ / -5 DEG C; 3) pressing pure Mg weighed in the step 1) into a melt obtained from the step 2) to stand for 3-5 minutes by a graphite bell jar with preheating temperature of 300 DEG C; 4) heating the melt obtained from the step 3) to be at 740-760 DEG C, adding weighed AlSc4 intermediate alloy till the intermediate alloy is completed melted, refining for 15 minutes by rotatably jetting high purity argon and drossing after standing for 10-20 minutes; 5) cooling the melt obtained from the step 4) to be at 680-700 DEG C and pouring into sand moulds, then cooling along with the mould to be at room temperature to obtain an as-cast structure containing fiberous and short-rod-shaped eutectic Si; and 6) performing heat treatment for cast obtained from the step 5) according to a T6 heat treatment process to obtain a particle eutectic silicon structure with good mechanical properties.

Description

technical field [0001] The invention relates to an alloy modification process, in particular to a hypoeutectic casting aluminum-silicon alloy modification process. Background technique [0002] Hypoeutectic aluminum-silicon alloy has been widely used to manufacture parts such as engine block, cylinder head, piston and cylinder liner because of its high specific strength, good wear resistance, corrosion resistance and casting performance. This type of alloy structure is mainly composed of α-Al phase, eutectic Si phase and a small amount of other intermetallic compounds, and the morphology and size of Si phase have a significant impact on its mechanical properties. The eutectic silicon in cast aluminum alloys is in the shape of thick needles or plates, which significantly reduces the strength and plasticity of the alloy, so it generally needs to be modified. The process of modification treatment is actually the process of changing the shape and size of eutectic silicon, that ...

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Problems solved by technology

[0003] Among the existing modifiers used for casting aluminum-silicon alloys, some have many chemical elements and high cost, and some have single functions, and do not have refining and modification effects at the same time; some are prone to produce a large amount of waste residue, and the corrosion performance of casting products is poor ; Some processing techniques are complicated, the operation is troublesome, and the work efficiency is low

In conventional production at present, among the most widely used sodium salt and potassium salt modifiers for hypoeutectic aluminum-silicon alloys, Cl and F ions have serious corrosion effects on iron crucibles, reducing the service life of crucibles; secondly, the boiling points of sodium and potassium Low, easy to volatilize at high temperature, short metamorphic time

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