Heat-treatment-free Al-Si series high-toughness die-casting aluminum alloy

Abstract

The invention discloses a heat-treatment-free Al-Si series high-toughness die-casting aluminum alloy which comprises the following components in percentage by weight: 6-11% of Si, 0.06-1% of Mg, 0.1-0.8% of Mn, 0.15-0.5% of Fe, 0.1-0.2% of Ti and less than or equal to 0.05% of trace elements besides aluminum, and specifically comprises the following alloy components: A < 1-8 > Si <-0.8 > Mn <-0.25 > Mg-Fe. According to the mechanical properties of the as-cast aluminum alloy, the tensile strength ranges from 275 MPa to 311 MPa, the yield strength ranges from 156 MPa to 174 MPa, the ductility ranges from 10.9% to 16.6%, the hardness value ranges from 96 HV to 115 HV, and the performance standard of castings for automobiles is met.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a heat - treatment - free Al - Si series high - strength and high - toughness die - casting aluminum alloy. Background Art

[0002] The integrated die - casting technology is a new revolution in die - casting technology. By using the integrated die - casting technology, multiple original independent castings and stamped parts can be integrated into a complete casting. On the basis of omitting subsequent processes such as welding and riveting of multiple original parts, the one - time forming of large - scale and complex castings can be completed. The integrated die - casting technology has obvious advantages in improving production efficiency, reducing weight, and lowering costs. Its technical core lies in the design and manufacture of large die - casting machines, the development of heat - treatment - free materials, the design of large - size die - casting dies, and the optimization of die - casting processes.

[0003] In the field of automotive lightweight engineering, die - casting aluminum alloys have become the core materials for manufacturing structural parts due to their lightweight characteristics, excellent specific strength, good filling ability, and comprehensive performance advantages. Industrial practice shows that Al - Si series and Al - Mg series alloys dominate the integrated die - casting material system due to their mature solidification defect control technology and process adaptability. Around these two alloy systems, domestic and foreign scholars have carried out systematic and in - depth research on alloy strengthening mechanisms and other aspects. At present, a variety of commercial aluminum alloy materials suitable for the integrated die - casting process have been developed in the market, which can meet the requirements of structural integration and lightweight to a certain extent. However, the theoretical research on non - heat - treated die - casting aluminum alloys is still relatively weak, and the material design and development of their high - strength and high - toughness properties still face many challenges, which is one of the key technical bottlenecks that need to be broken through urgently in this field.

[0004] The present invention proposes a new type of Al - Si series alloy, which can be used as a heat - treatment - free aluminum alloy for integrated die - casting forming. At the same time, during the melting process, the limited range of iron can be appropriately increased (0.15 - 0.50 wt.%), and the morphology and structure of Fe phase can be controlled by alloying methods, which can improve the application ratio of recycled aluminum in the raw materials for integrated die - casting. Summary of the Invention

[0005] The purpose of the present invention is to solve the drawbacks existing in the prior art, and to propose a heat - treatment - free Al - Si series high - strength and high - toughness die - casting aluminum alloy.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A heat - treatable Al - Si series high - strength and tough die - casting aluminum alloy, in addition to aluminum, further includes: Si (6 - 11%) wt.%, Mg (0.06 - 1%) wt.%, Mn (0.1 - 0.8%) wt.%, Fe (0.15 - 0.5%) wt.%, Ti (0.1 - 0.2%) wt.% and trace elements ≤ 0.05 wt.%

[0008] The above - mentioned technical solution further includes:

[0009] The specific alloy composition is: Al - 8Si - 0.8Mn - 0.25Mg - Fe.

[0010] The as - cast tensile strength of the Al - 8Si - 0.8Mn - 0.25Mg - Fe alloy is 275 - 311 MPa, the yield strength is 156 - 174 MPa, the elongation is 10.9 - 16.6%, and the hardness value is 96 - 115 HV.

[0011] The as - cast structure of the alloy consists of primary α1 - Al phase (ESCs) with large - sized dendritic morphology, spherical and near - spherical post - solidification α2 - Al phase, gray rod - shaped and worm - shaped eutectic Si phase, and Al(Fe,Mn)Si phase dispersedly distributed in a polygonal shape at the grain boundaries of α - Al phase and eutectic Si phase, where the α - Al phase is fine and uniform, and the average grain size ≤ 9.66 μm.

[0012] The room - temperature fracture mode of the as - cast Al - 8Si - 0.8Mn - 0.25Mg - Fe alloy is ductile fracture.

[0013] The present invention has the following beneficial effects:

[0014] In the present invention, based on the aluminum - silicon alloy, through the alloy ratio with the addition of trace amounts of magnesium and manganese elements, the mechanical properties of the as - cast aluminum alloy are as follows: the tensile strength is 275 - 311 MPa, the yield strength is 156 - 174 MPa, the elongation is 10.9 - 16.6%, and the hardness value is 96 - 115 HV, meeting the performance standards for automotive castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the first micro - structure diagram of a heat - treatable Al - Si series high - strength and tough die - casting aluminum alloy proposed by the present invention under a microscope;

[0016] Figure 2 It is the second micro - structure diagram of the aluminum alloy in the present invention under a microscope;

[0017] Figure 3 It is the third micro - structure diagram of the aluminum alloy in the present invention under a microscope;

[0018] Figure 4This is the fourth microstructure diagram of the aluminum alloy under the microscope in the present invention;

[0019] Figure 5 This is the fifth microstructure diagram of the aluminum alloy under the microscope in the present invention;

[0020] Figure 6 This is the sixth microstructure diagram of the aluminum alloy under the microscope in the present invention. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0022] Embodiment

[0023] In addition to aluminum, it also includes: Si (6-11%) wt.%, Mg (0.06-1%) wt.%, Mn (0.1-0.8%) wt.%, Fe (0.15-0.5%) wt.%, Ti (0.1-0.2%) wt.% and trace elements ≤ 0.05 wt.%. The specific alloy composition is: Al-8Si-0.8Mn-0.25Mg-Fe. The trace elements include one or more of Cu, Zn, Sr, Zr and Mo.

[0024] It is detected that the as-cast tensile strength of the Al-8Si-0.8Mn-0.25Mg-Fe alloy is 275-311 MPa, the yield strength is 156-174 MPa, the elongation is 10.9-16.6%, and the hardness value is 96-115 HV.

[0025] This alloy can be used as a heat-treatment-free aluminum alloy for integrated die-casting molding. At the same time, the defined range of iron (0.15-0.50 wt.%) can be appropriately increased during the melting process, and the morphology and structure of the Fe phase can be controlled by alloying methods, which can improve the application ratio of recycled aluminum in the raw materials for integrated die-casting.

[0026] The as-cast microstructure of the alloy consists of primary α1-Al phase (ESCs) with large-size dendritic morphology, spherical and near-spherical post-solidification α2-Al phase, gray rod-shaped and worm-shaped eutectic Si phase, and Al(Fe,Mn)Si phase dispersed in a polygonal shape at the grain boundaries of the α-Al phase and the eutectic Si phase. Among them, the α-Al phase is fine and uniform, and the average grain size ≤ 9.66 μm.

[0027] The room-temperature fracture mode of the as-cast Al-8Si-0.8Mn-0.25Mg-Fe alloy is ductile fracture.

[0028] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and permutations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An as-cast heat-treatable high strength and toughness Al-Si series die-casting aluminum alloy, characterized in that, In addition to aluminum, it also includes: Si (6 - 11%) wt.%, Mg (0.06 - 1%) wt.%, Mn (0.1 - 0.8%) wt.%, Fe (0.15 - 0.5%) wt.%, Ti (0.1 - 0.2%) wt.% and trace elements ≤ 0.05 wt.%.

2. The as-cast high-strength and tough die-casting Al-Si series aluminum alloy according to claim 1, wherein The specific alloy composition is: Al - 8Si - 0.8Mn - 0.25Mg - Fe.

3. The as-cast high-strength and tough die-casting Al-Si series aluminum alloy according to claim 1, wherein The trace elements include one or more of Cu, Zn, Sr, Zr and Mo.

4. A heat-treatable Al-Si series high-strength and tough die-casting aluminum alloy according to claim 1, characterized in that The as - cast tensile strength of the Al - 8Si - 0.8Mn - 0.25Mg - Fe alloy is 275 - 311 MPa.

5. A heat-treatment-free Al-Si-based high-strength and tough die-casting aluminum alloy according to claim 1, characterized in that The yield strength of the Al - 8Si - 0.8Mn - 0.25Mg - Fe alloy is 156 - 174 MPa.

6. The heat-treatment-free Al-Si-based high-strength and tough die-casting aluminum alloy according to claim 1, wherein The elongation of the Al - 8Si - 0.8Mn - 0.25Mg - Fe alloy is 10.9 - 16.6%.

7. An as-cast heat-treatable Al-Si-based high-strength and tough die-cast aluminum alloy according to claim 1, wherein The hardness value of the Al - 8Si - 0.8Mn - 0.25Mg - Fe alloy is 96 - 115 HV.

Images