CN113122739A

CN113122739A - Process method for improving mechanical property of A356 aluminum alloy

Info

Publication number: CN113122739A
Application number: CN202110290080.9A
Authority: CN
Inventors: 吴克桦; 朱才林; 向兴康
Original assignee: Jiangsu Ruimei Auto Parts Co ltd
Current assignee: Jiangsu Ruimei Auto Parts Co ltd
Priority date: 2021-03-18
Filing date: 2021-03-18
Publication date: 2021-07-16

Abstract

The invention discloses a process method for improving mechanical properties of an A356 aluminum alloy, which belongs to the technical field of materials, wherein the A356 aluminum alloy is modified by taking Al-10 wt% of Sb intermediate alloy as a modifier, and the addition amount of the modifier is 0.10-0.50% of the mass of the A356 aluminum alloy; after modification, the forms of the alpha solid solution dendrite network and the eutectic Si can be effectively improved, so that the alpha dendrite and the eutectic Si mass point become smaller, the elongation of the alloy is improved, and the mechanical property of the alloy is improved.

Description

Process method for improving mechanical property of A356 aluminum alloy

Technical Field

The invention relates to the technical field of materials, in particular to a process method for improving mechanical properties of A356 aluminum alloy.

Background

The A356 aluminum alloy is used as a good casting alloy material and is widely applied to the production of the integral casting wheel of the motorcycle and the car. According to the use requirements, the mechanical property index of the material should meet the requirements that the tensile strength is more than 200MPa and the elongation is more than 7 percent. However, in actual production, the block-cast wheel generally adopts a low-pressure casting process, an iron vortex-increasing tube and an iron lift tube are mostly used, the mass fraction of iron in the alloy cannot be guaranteed to be lower than 0.20%, the mass fraction of iron in the alloy can only be controlled to be close to 0.30%, the mechanical property of a casting is deteriorated, and particularly the elongation rate cannot meet the use requirement. The average yield strength, the breaking strength, the elongation and the reduction of area of the cast A356 aluminum alloy are 216.64MPa, 224MPa, 1.086 percent and 0.194 percent respectively at room temperature, the tensile yield strength of the alloy is reduced along with the increase of the distance from the plane of a pouring gate, the breaking strength is reduced and then increased, the elongation change along with the height is not obvious, and the elongation can not reach Be b more than or equal to 220MPa and delta more than or equal to 3 percent which are required by national standard ZL 101A.

Disclosure of Invention

The invention aims to provide a process method capable of effectively improving the mechanical property of A356 aluminum alloy.

The technical scheme of the invention is as follows: a process method for improving mechanical properties of A356 aluminum alloy is to use Al-10 wt% Sb intermediate alloy as modifier to modify A356 aluminum alloy, wherein the addition amount of the modifier is 0.10-0.50% of the mass of the A356 aluminum alloy.

According to a further technical scheme, a composite additive is further added in the casting process of the A356 aluminum alloy, and the composite additive is prepared from the following components in parts by mass (50-65): (2.5-3.8) 1 of silicon element, magnesium element and iron element.

According to a further technical scheme, the casting process of the A356 aluminum alloy comprises the following specific steps:

(1) preparing materials: taking A356 aluminum alloy as a raw material, and adding a composite additive into the A356 aluminum alloy;

(2) smelting: placing the ingredients in the step (1) in a resistance vortex furnace heated to 400-450 ℃, continuously heating the ingredients by the resistance vortex furnace to melt, heating to 690-730 ℃ after the ingredients are completely melted, and stirring the melt by using a graphite stick for 5-10min to ensure that elements in the melt are uniformly distributed;

(3) degassing: heating the resistance vortex-increasing furnace to 730-740 ℃, and introducing CCl6 for refining and degassing;

(4) modification treatment: adding a modifier into a resistance-increasing vortex furnace for modification treatment;

(5) solution treatment: and (3) cooling to 538 ℃, preserving the temperature for 8h, removing the surface scum, and then introducing the alloy into a metal mold for cooling to obtain the alloy.

The invention has the beneficial effects that:

the invention adopts the Al-10 wt% Sb intermediate alloy as the alterant, because the Sb element has rich resources, the Sb element is not easy to burn and lose due to the alteration, the alteration effect has long-acting property and remelting property, the AlSb compound is formed after the antimony is added, the compound is in a diamond structure, and the shape of an alpha solid solution dendrite network and eutectic Si can be effectively improved after the alteration, so that the alpha dendrite and the eutectic Si mass point are smaller, thereby improving the elongation of the alloy and improving the mechanical property of the alloy.

Drawings

Figure 1 is a stress-strain curve for example 1,

figure 2 is a stress-strain curve for example 2,

fig. 3 is a stress-strain curve of example 3.

Detailed Description

The invention will be further illustrated and understood by the following non-limiting examples.

The invention provides a process method for improving mechanical properties of A356 aluminum alloy, which comprises the following steps:

(1) preparing materials: taking A356 aluminum alloy as a raw material, and adding a composite additive into the A356 aluminum alloy; the composite additive comprises the following components in percentage by mass (50-65): (2.5-3.8) 1, namely silicon element, magnesium element and iron element;

(4) modification treatment: taking Al-10 wt% of Sb intermediate alloy as a modifier to modify the A356 aluminum alloy, wherein the addition amount of the modifier is 0.10-0.50% of the mass of the A356 aluminum alloy, and adding the modifier into a resistance-increasing vortex furnace to perform modification treatment;

Example 1

(1) preparing materials: taking A356 aluminum alloy as a raw material, and adding a composite additive into the A356 aluminum alloy; the composite additive is prepared from the following components in percentage by mass of 65: 3.8:1 of silicon element, magnesium element and iron element;

(2) smelting: placing the ingredients in the step (1) in a resistance vortex furnace heated to 400-450 ℃, continuously heating the ingredients by the resistance vortex furnace to melt, heating to 690-730 ℃ after the ingredients are completely melted, and stirring the melt for 10min by using a graphite stick to ensure that elements in the melt are uniformly distributed;

(4) modification treatment: taking Al-10 wt% of Sb intermediate alloy as a modifier to modify the A356 aluminum alloy, wherein the addition amount of the modifier is 0.10% of the mass of the A356 aluminum alloy, and adding the modifier into a resistance-increasing vortex furnace to perform modification treatment;

The alloy prepared in example 1 was subjected to a tensile test, the stress-strain curve of which is shown in fig. 1, and the test results are as follows: the tensile strength is 296.022Mpa, the yield strength is 258.461, and the elongation is 7.6%;

example 2

(1) preparing materials: taking A356 aluminum alloy as a raw material, and adding a composite additive into the A356 aluminum alloy; the composite additive is prepared from the following components in percentage by mass of 50: 2.5:1 of silicon element, magnesium element and iron element;

(4) modification treatment: taking Al-10 wt% of Sb intermediate alloy as a modifier to modify the A356 aluminum alloy, wherein the adding amount of the modifier is 0.50% of the mass of the A356 aluminum alloy, and adding the modifier into a resistance-increasing vortex furnace to perform modification treatment;

The alloy prepared in example 2 was subjected to a tensile test, the stress-strain curve of which is shown in fig. 2, and the test results are as follows: the tensile strength is 280.651Mpa, the yield strength is 258.656, and the elongation is 8.20%;

example 3

(1) preparing materials: taking A356 aluminum alloy as a raw material, and adding a composite additive into the A356 aluminum alloy; the composite additive is prepared from the following components in percentage by mass of 55: 3:1 of silicon element, magnesium element and iron element;

(4) modification treatment: taking Al-10 wt% of Sb intermediate alloy as a modifier to modify the A356 aluminum alloy, wherein the adding amount of the modifier is 0.30% of the mass of the A356 aluminum alloy, and adding the modifier into a resistance-increasing vortex furnace to perform modification treatment;

The alloy prepared in example 3 was subjected to a tensile test, the stress-strain curve of which is shown in fig. 3, and the test results are as follows: the tensile strength is 290.811Mpa, the yield strength is 277.894, and the elongation is 7.90%;

from the test results of examples 1 to 3, it can be seen that the tensile strength of the alloy is increased by adding Si, Mg and other impurity elements such as Fe during the melting of the alloy in step (2), but the elongation is decreased; according to the invention, Al-10 wt% Sb intermediate alloy is used as a modifier in the step (4), so that the forms of an alpha solid solution dendrite network and eutectic Si can be effectively improved, the mass points of alpha dendrite and eutectic Si are smaller, and the mechanical property of the alloy is improved;

in conclusion, the tensile strength of the alloy improved by the process method provided by the invention is more than 280MPa, the elongation is more than 7%, the alloy meets the national standard requirement of ZL101A, and the alloy is suitable for preparing automobile related castings.

Claims

1. A process method for improving mechanical properties of A356 aluminum alloy is characterized in that: al-10 wt% of Sb intermediate alloy is used as a modifier to modify the A356 aluminum alloy, and the addition amount of the modifier is 0.10-0.50% of the mass of the A356 aluminum alloy.

2. The process method for improving the mechanical property of the A356 aluminum alloy as claimed in claim 1, wherein the mechanical property of the A356 aluminum alloy is as follows: a356 aluminum alloy is also added with a composite additive in the casting process, and the composite additive is prepared from the following components in percentage by mass (50-65): (2.5-3.8) 1 of silicon element, magnesium element and iron element.

3. The process method for improving the mechanical property of the A356 aluminum alloy as claimed in claim 2, wherein the mechanical property of the A356 aluminum alloy is as follows: the specific process of casting the A356 aluminum alloy is as follows:

(3) degassing: heating the resistance vortex-increasing furnace to 730-740 ℃, and introducing CCl₆Refining and degassing;