KR20080102560A

KR20080102560A - Heat-resistant al alloy containing sn

Info

Publication number: KR20080102560A
Application number: KR1020070049165A
Authority: KR
Inventors: 강희삼
Original assignee: 현대자동차주식회사
Priority date: 2007-05-21
Filing date: 2007-05-21
Publication date: 2008-11-26

Abstract

The present invention relates to an aluminum alloy for a cylinder head in which Sn is added, by using a difference in chemical reactivity between Al and Sn, and Mg and Sn to uniformly generate a new intermetallic compound on an Al matrix, thereby making an aluminum alloy for an existing cylinder head. It is to provide a new alloy that significantly improved the room temperature and high temperature properties of the.

To this end, the present invention, in the existing multi-component heat-resistant aluminum alloy, the aluminum (Al) as the main component, the silicon (Si) 7-12% by weight, copper (Cu) 2-4% by weight, magnesium 0.2 ˜0.6% by weight of antimony, 0.2-0.4% by weight of antimony and other alloying elements such as Ti and Zr were added and cast 0.005 to 0.2% by weight of tin (Sn), followed by T6 heat treatment. Provided is a high heat-resistant aluminum alloy for a cylinder head to which Sn is added.

Description

Heat-resistant aluminum alloy for Sn-added cylinder head {Heat-resistant Al alloy containing Sn}

1 is a state diagram of Al-Sn and Mg-Sn binary system,

Figure 2 is a micrograph comparing the microstructure of the Sn-added alloy and the non-added alloy.

The present invention relates to a high heat-resistant aluminum alloy for a cylinder head with Sn added, and more particularly, Sn is added to significantly improve the mechanical properties of the aluminum alloy of AC2B or AC4CH series, which is a material for current cylinder heads. The high heat resistant aluminum alloy for the used cylinder head.

Recently, developed countries and countries around the world are making efforts to curb environmental pollution by strengthening various environmental regulations, and in order to cope with the ever-increasing environmental regulations, the automobile industry is continuously researching to improve fuel efficiency. The demand for higher power for engines is growing stronger.

As the engine became more powerful, the problem of damage due to the material limitation of AC2B or AC4CH alloy, which has been used for the existing cylinder head material, began to be revealed in the development process. It is difficult.

Therefore, much research has been conducted for strengthening the heat resistance of the existing aluminum alloy for cylinder head.

For example, various efforts have been attempted such as refinement of DAS of the cylinder head surface using cold metal during casting, spheroidization and refinement of primary Al by adding TiB ₂ , process Si improvement, and creation of new intermetallic compound through Mn addition. However, it is not enough to cope with the development of high combustion engines.

The present invention has been studied in view of the above-mentioned point, by adding Sn to the poly-based aluminum alloy to replace the aluminum alloy for the cylinder head that has reached the current material limit and applying the T6 heat treatment, Sn on the Al matrix By producing phase and Mg ₂ (Sn, Si, Sb) composite intermetallic compounds to provide a new heat-resistant aluminum alloy for cylinder heads with a 20% or more improvement in tensile strength compared to aluminum alloys for cylinder heads by dispersion strengthening effect. The purpose is.

In the present invention for achieving the above object, in the aluminum alloy for a cylinder head, aluminum (Al) as the main component, 7 to 12% by weight of silicon (Si), 2 to 4% by weight of copper (Cu), magnesium (Mg) 0.2 ~ 0.6% by weight, antimony (Sb) 0.2 ~ 0.4% by weight, tin (Sn) after the addition of the cast, after the addition of the T6 heat treatment for the cylinder head Sn added, characterized in that Provides a high heat resistant aluminum alloy.

Hereinafter, the present invention will be described in more detail.

The present invention does not have a chemical affinity with Al in order to create a new intermetallic compound that is stable at high temperature on the microstructure of the multi-element aluminum alloy, 0.005 ~ 0.2% by weight of Sn has a high chemical affinity with Mg, an alloying element, It is intended to improve the strength and heat resistance by inducing the production of Mg (Sn, Sb, Si) intermetallic compound in a quantitative amount larger than the existing Mg (Sb, Si).

To this end, the present invention has aluminum (Al) as a main component, silicon (Si) 7-12% by weight, copper (Cu) 2-4% by weight, magnesium (Mg) 0.2-0.6% by weight, antimony 0.2- The present invention provides an aluminum alloy in which 0.45 wt% to 0.2 wt% of tin (Sn) is added to a multi-component aluminum alloy including 0.4 wt% and other alloying elements Ti, Zr, and the like, followed by T6 heat treatment.

At this time, the amount of Sn added may be added from 0.005% by weight to 0.2% by weight depending on the content of Mg, but less than 0.005% by weight, the effect is insignificant, when 0.2% by weight or more coarse Sn phase is formed on the microstructure It is desirable to add a minimum amount for the production of new intermetallic compounds, since deterioration in mechanical properties can result.

Through such Sn addition, it is possible to provide a new high-heat-resistant aluminum alloy for the cylinder head has improved tensile and fatigue properties 20% or more compared to the existing aluminum alloy for the cylinder head.

1 is a state diagram of Al-Sn and Mg-Sn alloys.

Referring to FIG. 1, Al and Sn form a mononotectic system having no mutual chemical reactivity, which means that Al and Sn exist in a liquid state as a relationship between water and oil.

In contrast, Mg and Sn form Mg ₂ Sn intermetallic compounds in the vicinity of 70% by weight Sn.

Based on the characteristics of Sn, Sn was added to the existing polycyclic aluminum alloy, and as a result, the microstructure change as shown in FIG. 2 was confirmed.

As can be seen in Figure 2, it can be seen that a new intermetallic compound is formed on the microstructure by the addition of Sn, and when Sn is not added, as shown in (a) of FIG. While a small amount of Si) is distributed, when Sn is added, as shown in FIG. 2 (b), many new Mg (Sn, Sb, Si) intermetallic compounds are crystallized, and some Sn reacts with other alloying elements. Rather, it is produced in the form of fine precipitates in the Al matrix.

This microstructural change directly affects mechanical properties, which is much larger than the reinforcing effect of Mg (Sb, Si) caused by the existing Sb addition, and thus improved high strength compared to the conventional multicomponent alloys. In addition, it is possible to provide a new alloy with high heat resistance.

Hereinafter, the embodiment of the present invention will be described in more detail with a comparative example, but the present invention is not limited to the following examples.

Examples and Comparative Examples

Here, as examples and comparative examples for confirming the Sn addition effect, NS10 alloy of Nippon Light Metal was used, and the results of the component ratio analysis are shown in Table 1 below.

The alloy according to the embodiment of the present invention is Al as a main component, and 9.54% by weight of Si, 3.58% by weight of Cu, 0.48% by weight of Mg, 0.29% by weight of Sb, and 0.012% by weight of Sn are added. The resulting alloy is shown.

On the other hand, the alloy (Al-7Si-0.4Mg) according to the comparative example has Al as a main component, and 9.61% by weight of Si, 3.64% by weight of Cu, 0.46% by weight of Mg, and 0.31% by weight of Sb are added, and after casting, T6 The alloy of the result of heat processing is shown.

Test Example

As a test example, the strength change by the Sn addition of the above-mentioned Example and Comparative Example alloys was measured by a conventional equipment, and the results are shown in Table 2.

As shown in Table 2 above, it was confirmed that the tensile strength of the new alloy according to the embodiment of the present invention improved by 5 to 10% or more due to the change in the microstructure. It was confirmed that the material can be obtained.

As described above, according to the high-heat-resistant aluminum alloy for Sn-added cylinder head according to the present invention, through the addition of tin (Sn) and T6 heat treatment, a new metal on the microstructure of the existing high-heat-resistant multi-element aluminum alloy Mg (Sn, Sb, Si), a hepatic compound, can be produced to increase the strength by more than 10% by adding dispersion strengthening effect to the existing precipitation strengthening effect, and can be applied to high power and high combustion pressure new engine heads to be developed in the future. There is an advantage that can be widely used as a high strength, high heat resistant material.

Claims

In the aluminum alloy for the cylinder head,

Aluminum (Al) is the main component, and silicon (Si) 7-12 wt%, copper (Cu) 2-4 wt%, magnesium (Mg) 0.2-0.6 wt%, antimony (Sb) 0.2-0.4 wt% And tin (Sn) added by 0.005 to 0.2% by weight, and then cast, followed by T6 heat treatment.